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ADSL - An acronym for Asymmetric Digital Subscriber Line. ADSL is technology that allows more data to be sent over existing copper telephone lines. ADSL supports data rates of from 128 kilobits per second to 9 megabits per second when receiving data (known as the downstream rate) and from 16 kilobits per second to 4 megabits per second when sending data (known as the upstream rate). ADSL requires a special ADSL modem. (Also see xDSL)
Bandwidth - The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second(Bps).
Bit - An abbreviation for binary digit. A bit is the smallest unit of information on any machine. A single bit can hold only one of two values: 0 or 1. More meaningful information is obtained by combining consecutive bits into larger units. For example, a byte is composed of 8 consecutive bits.
bps - An acronym for bits per second. This is the standard measurement of data transmission speeds, mainly used for bandwidth speeds.
Bps - An acronym for bytes per second. This is a more popular form of measurement of data transmission speeds.
Broadband - A type of data transmission in which a single medium (wire) can carry several channels at once. Cable TV, for example, uses broadband transmission.
Byte - An abbreviation for binaryterm. It's a unit of storage capable of holding a single character. On almost all modern computers, a byte is equal to 8 bits. Large amounts of memory are indicated in terms of kilobytes, megabytes, and gigabytes.
Cable - Through the use of a cable modem you can have a broadband Internet connection that is designed to operate over cable TV lines. Cable Internet works by using TV channel space for data transmission, with certain channels used for downstream transmission, and other channels for upstream transmission. Because the coaxial cable used by cable TV provides much greater bandwidth than telephone lines, a cable modem can be used to achieve extremely fast access to the Web. This, combined with the fact that millions of homes are already wired for cable TV, has made cable Internet service something cable TV companies have really jumped onboard with.
Choked - When a connection is choked, it means that the transmitter isn't currently sending anything else on the link. A BitTorrent Client signals that it's choked to other clients for a number of reasons, the most common is that by default a client will only maintain -- max_uploads active simultaneous uploads, the rest will be marked choked. A connection can also be choked for other reasons, for example a peer downloading from a seed will mark his connection as choked since the seed has no need to receive. (Also see Snubbed)
Client - The client part of a client-server architecture. Typically, a client is an application that runs on a personal computer or workstation and relies on a server to perform some operations. More commonly referred to as a BitTorrent client in the torrent community.
Credit System - A forced sharing situation that attempts to eliminate leechers. In this system a user is given credit towards downloading for each upload made. (See also Ratio)
Data - Distinct pieces of information, usually formatted in a special way. All software is divided into two general categories: data and programs. Programs are collections of instructions for manipulating data. Data can exist in a variety of forms -- as numbers or text on pieces of paper, as bits and bytes stored in electronic memory, or as facts stored in a person's mind. Strictly speaking, data is the plural of datum, a single piece of information. In practice, however, people use data as both the singular and plural form of the word.
Decentralized Network - A network topology where each user of the network is able to distribute information and queries directly through other users of the network rather than relying on a central server to act as an indexing agent.
DHCP - An acronym for Dynamic Host Configuration Protocol. This is a protocol for assigning dynamic IP addresses to devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network. In some systems, the device's IP address can even change while it is still connected. DHCP also supports a mix of static and dynamic IP addresses. Dynamic addressing simplifies network administration because the software keeps track of IP addresses rather than requiring an administrator to manage the task. This means that a new computer can be added to a network without the hassle of manually assigning it a unique IP address.
DHT - An acronym for Distributed Hash Tables. These are a class of decentralized, distributed systems and algorithms being developed to provide a scalable, self-configuring infrastructure with a clean programming interface. This infrastructure can then be used to support more complex services. DHTs can be used to store data, as well as route and disseminate information. DHTs are named after hash tables because they assign responsibility for a piece of data based on a hash function (often SHA-1); each node acts like a bucket in a hash table. A DHT provides an efficient lookup algorithm (or network routing method) that allows one participating node to quickly determine which other machine is responsible for a given piece of data.
Distributed Copies - In some versions of the client, you will see "Connected to x seeds; also seeing x.xxx distributed copies." A seed is a computer with the complete file. However, the swarm can collectively have a complete copy (or copies) of the file, even without seeds a complete distributed copy can be available if the sum total of the users have a complete copy among themselves. BitTorrent doesn't distribute in sequential order, so this is possible.
Distributed Hash - A technology that can be used to develop a common infrastructure for distributed or peer-to-peer applications, including storage and multicasting. (See also DHT)
Download - To copy data (usually an entire file) from a main source to a peripheral device. The term is often used to describe the process of copying a file from an online service or bulletin board service (BBS) to one's own computer. Downloading can also refer to copying a file from a network file server to a computer on the network. (Also see Downstream)
Downstream - A transmission from a server to an end user. A downstream transmission can be in the form of a signal being transmitted from a server to a workstation across a network, such as a LAN, or a signal being sent from a cable service provider to a customer. (Also see Download)
DSL - An acronym for Digital Subscriber Line. (Also see xDSL)
Dynamic - Refers to actions that take place at the moment they are needed rather than in advance. For example, you are not assigned an IP address from your ISP, until you connect to your ISP. Once you disconnect, that IP address you were assigned, is sent back to the IP pool. When you connect again, you will be given a different IP address than the last one you were assigned.
E1 - Similar to the North American T1, E1 is the European format for digital transmission. E1 carries signals at 2 Mbps (32 channels at 64Kbps, with 2 channels reserved for signaling and controlling), versus the T1, which carries signals at 1.544 Mbps (24 channels at 64Kbps). E1 and T1 lines may be interconnected for international use.
Encryption - The translation of data into a secret code. Encryption is the most effective way to achieve data security. To read an encrypted file, you must have access to a secret key or password that enables you to decrypt it. Unencrypted data is called plain text ; encrypted data is referred to as cipher text. There are two main types of encryption: asymmetric encryption (also called public-key encryption) and symmetric encryption.
File - A collection of data or information that has a name, called the filename. Almost all information stored in a computer must be in a file. There are many different types of files: data files, text files, program files, directory files, and so on. Different types of files store different types of information. For example, program files store programs, whereas text files store text.
File Sharing - The act of BOTH receiving AND sending of files to other users. This is different from someone who only receives files, called a leeching.
Firewall - A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria. (For more information, please see Firewall)
FiOS - An acronym for Fiber Optic Service. An internet service which uses optic fiber for data transfers. (Also see Optic fiber)
Gb - An abbreviation for gigabit. There are 1073741824 bits in (1) gigabit. (Also see Gigabit)
GB - An abbreviation for gigabyte. There are 1073741824 bytes in (1) gigabyte. (Also see Gigabyte)
Gigabit - Used to describe data storage. (Also see Gb)
Gigabyte - Used to describe data storage. (Also see GB)
Hash(ing) - Producing hash values for accessing data or for security. A hash value (or simply hash), also called a message digest, is a number generated from a string of text. The hash is substantially smaller than the text itself, and is generated by a formula in such a way that it is extremely unlikely that some other text will produce the same hash value. Hashes play a role in security systems where they're used to ensure that transmitted messages have not been tampered with. The sender generates a hash of the message, encrypts it, and sends it with the message itself. The recipient then decrypts both the message and the hash, produces another hash from the received message, and compares the two hashes. If they're the same, there is a very high probability that the message was transmitted intact.
HDSL - An acronym for High data rate Digital Subscriber Line. HDSL is an international standard for symmetric DSL developed by the International Telecommunication Union (ITU). HDSL provides for sending and receiving high-speed symmetrical data streams over a single pair of copper wires at rates between 192 KBps and 2.31 MBps. HDSL was developed to incorporate the features of other DSL technologies, such as ADSL and SDSL and will transport T1, E1, ISDN, ATM and IP signals. (Also see xDSL)
HTTP - An acronym for HyperText Transfer Protocol. HTTP is the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page. In the world of BitTorrent, a HTTP torrent is a torrent tracked by a tracker using the TCP ports.
Hub - A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets. A passive hub serves simply as a conduit for the data, enabling it to go from one device (or segment) to another. So-called intelligent hubs include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub. Intelligent hubs are also called manageable hubs. A third type of hub, called a switching hub, actually reads the destination address of each packet and then forwards the packet to the correct port.
Intrested - Term used in the protocol specification. Refers to the state of a downloader with respect to a connection. A downloader is marked as interested if the other end of the link has any pieces that the client wants, otherwise the connection is marked as not interested.
IP - An acronym for Internet Protocol. IP specifies the format of packets, also called datagrams, and the addressing scheme. IP by itself, is something like the postal system. It allows you to address a package and drop it in the system, but there's no direct link between you and the recipient.
IP address - An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 126.96.36.199 could be an IP address. Within an isolated network, you can assign IP addresses at random as long as each one is unique. However, connecting a private network to the Internet requires using registered IP addresses (called Internet addresses) to avoid duplicates.
ISDN - An acronym for Integrated Services Digital Network. This is an international communications standard for sending voice, video, and data over digital telephone lines or normal telephone wires. ISDN supports data transfer rates of 64 Kbps (64,000 bits per second). The original version of ISDN employs baseband transmission. Another version, called B-ISDN, uses broadband transmission and is able to support transmission rates of 1.5 Mbps. B-ISDN requires fiber optic cables and is not widely available.
ISP - An acronym for Internet Service Provider. These are companies that provides access to the Internet. For a monthly fee, the service provider gives you a software package, username, password and access phone number(s) (for dial-up). Equipped with a modem, you can then log on to the Internet and browse the World Wide Web and USENET, and send and receive e-mail. In addition to serving individuals, ISPs also serve large companies, providing a direct connection from the company's networks to the Internet. ISPs themselves are connected to one another through Network Access Points (NAPs). ISPs are also called IAPs (Internet Access Providers).
kb - An abbreviation for kilobit. There are 1024 bits in (1) kilobit. (Also see Kilobit)
Kb - An abbreviation for kilobyte. There are 1024 bytes in (1) kilobyte. (Also see Kilobyte)
Kbps - An acronym for Kilobits per second. (Also see bps)
KBps - An acronym for Kilobytes per second. (Also see Bps)
Kilobit - Used to describe data storage. (Also see kb)
Kilobyte - Used to describe data storage. (Also see Kb)
LAN - An acronym for Local Area Network. A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. Most LANs connect workstations and personal computers. Each node (individual computer ) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN. (For more information, see LAN) (Also see WAN)
Leech(er) - A file-sharing user that does not allow others to download from him and only takes from others is a LEECH. And remember folks, nobody likes a leecher
Locally Queued - The amount of files you permit to simultaneously download is referred to as your local queue.
mb - An abbreviation for megabit. There are 1048576 bits in (1) megabit. (Also see Megabit)
MB - An abbreviation for megabyte. There are 1048576 bytes in (1) megabyte. (Also see Megabyte)
Mbps - An acronym for megabits per second. This is a standard measurement of data transmission speeds, mainly used for bandwidth speeds.
MBps - An acronym for megabytes per second.
Megabit - Used to describe data storage. (Also see mb)
Megabyte - Used to describe data storage. (Also see MB)
MPAA - An acronym for Motion Pictures Association of America. The MPAA, originally called the Motion Pictures Producers and Distributors Association, is a non-profit trade association based in the United States which was formed to advance the interests of movie studios. Its members consist of seven major studios: the Walt Disney Company, Sony Pictures, Metro-Goldwyn-Mayer, Paramount Pictures, Twentieth Century Fox, Universal Studios, and Warner Bros. The organization produces the well-known voluntary film rating system. This is an organization who attempts to fight piracy. Visit the MPAA home page for more information, as well as contact information to send hate mail.
MultiSource - Multi-source is a term that describes the transfer of a file that is downloaded from two or more locations.
NAT - An acronym for Network Address Translation. This is an Internet standard that enables a local-area network (LAN) to use one set of IP addresses for internal traffic and a second set of addresses for external traffic. A NAT box located where the LAN meets the Internet makes all necessary IP address translations.
NAT serves three main purposes:
- Provides a type of firewall by hiding internal IP addresses
- Enables a company to use more internal IP addresses. Since they're used internally only, there's no possibility of conflict with IP addresses used by other companies and organizations.
- Allows a company to combine multiple ISDN connections into a single Internet connection.
Newbie - Although originally designed to describe "newbies" to the gaming scene, this is now a general term to describe anyone who is consistent with being or acting stupid. Also used the same way, is newb, noob, and noobie.
NFO - Pronounced like 'info'. That is exactly what it means also. This can also be a file with a .nfo extension. These are ascii text files that describe a release of some sort (program, movie, game, album, etc.) .nfo files can be viewed in any text editor/viewer, but are best viewed by an ascii text enabled editor/viewer.
Octet - An octet is 8 bits. It is equivalent to a byte, as long as the byte is also 8 bits. Bytes range from 4 - 10 bits, but octets are always 8 bits.
Optic fiber - An optical fiber (or fibre) is a transparent thin fiber, usually made of glass or plastic, for transmitting light. Fiber optics is the branch of science and engineering concerned with such optical fibers. For more information, see Optic Fiber. (Also see FiOS)
Optimistic Unchoking - Periodically, the client shakes up the list of uploaders and tries sending on different connections that were previously choked, and choking the connections it was just using. You can observe this action every 10 or 20 seconds or so, by watching the "Advanced" panel of one of the experimental clients.
P2P - An abbreviation of Peer-to(2)-Peer. This is a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler, but they usually do not offer the same performance under heavy loads.
Peer(s) - A peer is another computer on the internet that is sharing the file you wish to download. Typically a peer does not have the complete file, if it did it would be called a seed. Peers are also called leeches, to distinguish them from those who have completed their download and continue to leave their BitTorrent Client running and act as a seed.
PeerGuardian - PeerGuardian is a program that acts as a firewall against known malicious sources (IP ranges of the RIAA and MPAA for example). Using this software one can take one step in protecting oneself from the tactics employed by these organizations.
Port(s) - In TCP/IP and UDP networks, an endpoint to a logical connection. The port number identifies what type of port it is. For example, port 80 is used for HTTP traffic.
PPPoE - An acronym for Point to Point Protocol over Ethernet. PPPoE relies on two widely accepted standards: PPP and Ethernet. PPPoE is a specification for connecting the users on an Ethernet to the Internet through a common broadband medium, such as a single DSL line, wireless device or cable modem. All the users over the Ethernet share a common connection, so the Ethernet principles supporting multiple users in a LAN combine with the principles of PPP, which apply to serial connections.
Protocol - This is an agreed-upon format for transmitting data between two devices.
The protocol determines the following:
- the type of error checking to be used
- data compression method, if any
- how the sending device will indicate that it has finished sending a message
- how the receiving device will indicate that it has received a message
There are a variety of standard protocols from which programmers can choose. Each has particular advantages and disadvantages; for example, some are simpler than others, some are more reliable, and some are faster. From a user's point of view, the only interesting aspect about protocols is that your computer or device must support the right ones if you want to communicate with other computers. The protocol can be implemented either in hardware or in software.
Proxy Server - This is a server that sits between a client application, such as a Web browser, and a real server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server.
Proxy servers have two main purposes:
- Improve Performance: Proxy servers can dramatically improve performance for groups of users. This is because it saves the results of all requests for a certain amount of time. Consider the case where both user X and user Y access the World Wide Web through a proxy server. First user X requests a certain Web page, which we'll call Page 1. Sometime later, user Y requests the same page. Instead of forwarding the request to the Web server where Page 1 resides, which can be a time-consuming operation, the proxy server simply returns the Page 1 that it already fetched for user X. Since the proxy server is often on the same network as the user, this is a much faster operation. Real proxy servers support hundreds or thousands of users. The major online services such as Compuserve and America Online, for example, employ an array of proxy servers.
- Filter Requests: Proxy servers can also be used to filter requests. For example, a company might use a proxy server to prevent its employees from accessing a specific set of Web sites.
Query - This is a request for information from a database. There are three general methods for posing queries:
- Choosing parameters from a menu: In this method, the database system presents a list of parameters from which you can choose. This is perhaps the easiest way to pose a query because the menus guide you, but it is also the least flexible.
- Query by example (QBE): In this method, the system presents a blank record and lets you specify the fields and values that define the query.
- Query language: Many database systems require you to make requests for information in the form of a stylized query that must be written in a special query language. This is the most complex method because it forces you to learn a specialized language, but it is also the most powerful.
Queue - There are a few meanings for queue.
- In computer science, queuing refers to lining up jobs for a computer or device. For example, if you want to print a number of documents, the operating system (or a special print spooler) queues the documents by placing them in a special area called a print buffer or print queue. The printer then pulls the documents off the queue one at a time. Another term for this is print spooling. The order in which a system executes jobs on a queue depends on the priority system being used. Most commonly, jobs are executed in the same order that they were placed on the queue, but in some schemes certain jobs are given higher priority.
- In programming, a queue is a data structure in which elements are removed in the same order they were entered. This is often referred to as FIFO (first in, first out). In contrast, a stack is a data structure in which elements are removed in the reverse order from which they were entered. This is referred to as LIFO (last in, first out).
- In the P2P community, a queue is a first in, first out order that is kept to allow only a certain amount of uploads at a time. Also, at which downloads execute first.
Ratio - A ratio of your amount uploaded divided by your amount downloaded. The amounts used are for the current session only, not over the history of the file. If you achieve a share ratio of 1.0, that would mean you've uploaded as much as you've downloaded. The higher the number, the more you have contributed. If you see a share ratio of ∞ (infinity), this happened because you opened a BitTorrent Client with a complete file (i.e., you seed the file.). In this case you download nothing since you have the full file, and so anything you send will cause the ratio to reach infinity. While share ratings are just displayed for your convenience, courtesy to others should cause you to keep this ratio as high as possible. (Also see Credit System)
Reseed - When there are zero seeds for a given torrent (and not enough peers to have a distributed copy), all the peers will get stuck with an incomplete file, since no one in the swarm has the missing pieces. When this happens, someone with a complete file (a seed) must connect to the swarm so that those missing pieces can be transferred. This is called reseeding. Usually a request for a reseed comes with an implicit promise that the requester will leave his or her client open for some time period after finishing (to add longevity to the torrent).
RIAA - An acronym for The Recording Industry Association of America. The RIAA is the trade group that represents the recording industry in the United States. The RIAA has continued to participate in creating and administering technical standards for later systems of music recording and reproduction, including magnetic tape, cassette tapes, digital audio tapes, CDs, and software-based digital technologies. The RIAA also participates in the collection, administration and distribution of music licenses and royalties. The association is responsible for certifying gold and platinum albums and singles in the USA. For more information about sales data see list of best selling albums and list of best selling singles. The RIAA has been at the heart of the file-sharing controversy, especially music files in the popular MP3 format uploaded onto the Internet using peer-to-peer software. The RIAA has long contended that sharing of copyrighted music was a form of piracy, applying the well-known computing term to music. Visit the RIAA home page for more information, as well as contact information to send hate mail.
SDSL - An acronym for Symmetric Digital Subscriber Line. This is a technology that allows more data to be sent over existing copper telephone lines. SDSL supports data rates up to 10 Mbps. SDSL works by sending digital pulses in the high-frequency area of telephone wires and can not operate simultaneously with voice connections over the same wires. SDSL requires a special SDSL modem. SDSL is called symmetric because it supports the same data rates for upstream and downstream traffic. A similar technology that supports different data rates for upstream and downstream data is called asymmetric digital subscriber line (ADSL). ADSL is more popular in North America, whereas SDSL is being developed primarily in Europe. (Also see xDSL)
Seed(er) - A computer that has a complete copy of the specific torrent you are downloading. Once your client finishes downloading, it will remain open until you click the Finish button. This is known as seeding. You can also start a BitTorrent Client with a complete file, and once BitTorrent has checked the file it will connect and seed the file to others. It is good to continue seeding a file after you have finished downloading, to help others finish. Also, when a new torrent is posted to a tracker, someone must seed it in order for it to be available to others. The tracker doesn't know anything of the actual contents of a file, so it's important to follow through and seed a file if you upload the torrent to a tracker.
Server - A computer or device on a network that manages network resources. For example, a file server is a computer and storage device dedicated to storing files. Any user on the network can store files on the server. A print server is a computer that manages one or more printers, and a network server is a computer that manages network traffic. A database server is a computer system that processes database queries. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. On multiprocessing operating systems, however, a single computer can execute several programs at once. A server in this case could refer to the program that is managing resources rather than the entire computer.
Share rating - (See Ratio)
Snubbed - If the client has not received anything after a certain period (default: 60 seconds), it marks a connection as snubbed, in that the peer on the other end has chosen not to send. The real function of keeping track of this variable is to improve download speeds. Occasionally the client will find itself in a state where even though it is connected to many peers, it is choked by all of them. The client uses the snubbed flag in an attempt to prevent this situation. It notes that a peer with whom it would like to trade pieces with has not sent anything in a while, and rather than leaving it up to the optimistic choking to eventually select that peer, it instead reserves one of its upload slots for sending to that peer. (Also see Choked)
SOCKS - A protocol for handling TCP traffic through a proxy server. It can be used with virtually any TCP application, including Web browsers and FTP clients. It provides a simple firewall because it checks incoming and outgoing packets and hides the IP addresses of client applications. There are two main versions of SOCKS -- V4 and V5. V5 adds an authentication mechanism for additional security. There are many freeware implementations of both versions. One of the most common V5 implementations is SOCKS5.
Static - Generally refers to elements of the Internet or computer programming that are fixed and not capable of action or change. A Web site that is static can only supply information that is written into the HTML and this information will not change unless the change is written into the source code. When a Web browser requests the specific static Web page, a server returns the page to the browser and the user only gets whatever information is contained in the HTML code. Similarly, a static IP, will always remain the same, regardless of if/when you disconnect.
Swarm - The group of users that are collectively connected for a particular file. Example, if you start a BitTorrent Client and it tells you that you're connected to 5 peers and 1 seeds, then the swarm consists of you and those 6 other people.
T1 - A dedicated phone connection supporting data rates of 1.544 Mbps per second. A T-1 line actually consists of 24 individual channels, each of which supports 64Kbits per second. Each 64Kbit/second channel can be configured to carry voice or data traffic. Most telephone companies allow you to buy just some of these individual channels, known as fractional T-1 access. T-1 lines are a popular leased line option for businesses connecting to the Internet and for Internet Service Providers (ISPs) connecting to the Internet backbone. The Internet backbone itself consists of faster T-3 connections. T-1 lines are sometimes referred to as DS1 lines.
T3 - A dedicated phone connection supporting data rates of about 43 Mbps. A T-3 line actually consists of 672 individual channels, each of which supports 64 Kbps. T-3 lines are used mainly by Internet Service Providers (ISPs) connecting to the Internet backbone and for the backbone itself. T-3 lines are sometimes referred to as DS3 lines.
Tb - An abbreviation for terabit. There are 1099511627776 bits in (1) terabit. (Also see Terabit)
TB - An abbreviation for terabyte. There are 1099511627776 bytes in (1) terabyte. (Also see Terabyte)
TCP - An acronym for Transmission Control Protocol. TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent.
TCP/IP - An acronym for Transmission Control Protocol / Internet Protocol. This is the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. Even network operating systems that have their own protocols, such as Netware, also support TCP/IP.
Terabit - Used to describe data storage. (Also see Tb)
Terabyte - Used to describe data storage. (Also see TB)
Torrent - A small metadata file which contains information about the data you want to download, not the data itself. It is downloaded from a web site (BitTorrent file extension is .torrent) by clicking on a download link. It can also be saved to your computer. This is useful if you want to be able to re-open the torrent later on without having to find the link again.
Tracker - Server on the Internet that coordinates the action of BitTorrent Clients. Upon opening a torrent, you contact the tracker and receive a list of peers to connect to. Throughout the transfer, your computer will query the tracker, telling it how much you've downloaded and uploaded and how much before finishing. If a tracker is down and you try to open a torrent, you will be unable to connect. If a tracker goes down during a torrent (you have already connected at some point and are already talking to peers), you will be able to continue transferring with those peers, but no new peers will be able to contact you. Tracker errors are often temporary, leave the client open and continue trying.
UDP - An acronym for User Datagram Protocol. This a connectionless protocol that, like TCP, runs on top of IP networks. Unlike TCP/IP, UDP/IP provides very few error recovery services, offering instead a direct way to send and receive datagrams over an IP network. It's used primarily for broadcasting messages over a network. In the world of BitTorrent, a UDP torrent is a torrent tracked by a tracker using the UDP ports.
Upload - To transmit data from a computer to a bulletin board service, mainframe, or network. For example, if you use a personal computer to log on to a network and you want to send files across the network, you must upload the files from your PC to the network. (Also see Upstream)
Upstream - A transmission from an end user to a server. An upstream transmission can be in the form of a signal being transmitted from a workstation to a server across a network, such as a LAN, or a signal being sent from a customer to a cable service provider. (Also see Upload)
UPnP - An acronym for Universal Plug and Play. This is a networking architecture that provides compatibility among networking equipment, software and peripherals of the 400+ vendors that are part of the Universal Plug and Play Forum. UPnP works with wired or wireless networks and can be supported on any operating system. UPnP boasts device-driver independence and zero-configuration networking.
URL - An acronym for Uniform Resource Locator. This is the global address of documents and other resources on the World Wide Web. The first part of the address indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located.
VDSL - An acronym for Very High Speed Digital Subscriber Line. DSL transmits data in the 13 Mbps - 55 Mbps range over short distances, usually between 1000 and 4500 feet (300 - 1500 meters), of twisted pair copper wire. The shorter the distance, the faster the connection rate. As the final length of cable into the home or office, VDSL connects to neighborhood Optical Network Units (ONUs), which connect to the central office's main fiber network backbone. This architecture will allow VDSL users to access the maximum bandwidth available through normal phone lines. VDSL is currently going through a standards issue, so it isn't widely deployed yet. The VDSL alliance favors a line coding scheme based on Discrete Multitone (DMT), a multi-carrier system that is more compatible with existing ADSL technology. The VDSL coalition favors a line coding scheme based on Quadature Amplitude Modulation (QAM), a single-carrier system that is less expensive and consumes less power. (Also see xDSL)
WAN - An acronym for Wide-Area Network. This is a computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs). Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet. (Also see LAN)
WiFi - An abbreviation of Wireless Fidelity. This is meant to be used generically when referring of any type of 802.11 network, whether 802.11b, 802.11a, dual-band, etc.
xDSL - This refers collectively to all types of digital subscriber lines, the two main categories being ADSL and SDSL. Two other types of xDSL technologies are High-data-rate DSL (HDSL) and Very high DSL (VDSL). DSL technologies use sophisticated modulation schemes to pack data onto copper wires. They are sometimes referred to as last-mile technologies because they are used only for connections from a telephone switching station to a home or office, not between switching stations. xDSL is similar to ISDN in as much as both operate over existing copper telephone lines (POTS) and both require the short runs to a central telephone office (usually less than 20,000 feet). However, xDSL offers much higher speeds - up to 32 Mbps for downstream traffic, and from 32 Kbps to over 1 Mbps for upstream traffic.