IP Address Definition An IP address, or simply an "IP," is a unique address that identifies a device on the Internet or a local network. It allows a system to be recognized by other systems connected via the Internet protocol. There are two primary types of IP address formats used today — IPv4 and IPv6. IPv4 An IPv4 address consist of four sets of numbers from 0 to 255, separated by three dots. For example, the IP address of TechTerms.com is 67.43.14.98. This number is used to identify the TechT...

UDP Definition Stands for "User Datagram Protocol." It is part of the TCP/IP suite of protocols used for data transferring. UDP is a known as a "stateless" protocol, meaning it doesn't acknowledge that the packets being sent have been received. For this reason, the UDP protocol is typically used for streaming media. While you might see skips in video or hear some fuzz in audio clips, UDP transmission prevents the playback from stopping completely.

VCI Definition Stands for "Virtual Channel Identifier." The VCI, used in conjunction with the VPI (virtual path indicator), indicates where an ATM cell is to travel over a network. ATM, or asynchronous transfer mode, is a method that many ISPs (Internet Service Providers) use to transfer data to client computers. Because ATM sends packets over fixed channels, the data is easier to track than information sent over the standard TCP/IP protocol. The VCI within each ATM cell defines the fixed chann...

Datagram Definition Datagram is a combination of the words data and telegram. Therefore, it is a message containing data that is sent from location to another. A datagram is similar to a packet, but does not require confirmation that it has been received. This makes datagrams ideal for streaming services, where the constant flow of data is more important than 100% accuracy. Datagrams are also called "IP datagrams" since they are used by the Internet protocol (IP). This protocol defines how info...

Packet Definition A packet is a small amount of data sent over a network, such as a LAN or the Internet. Similar to a real-life package, each packet includes a source and destination as well as the content (or data) being transferred. When the packets reach their destination, they are reassembled into a single file or other contiguous block of data. While the exact structure of a packet varies between protocols, a typical packet includes two sections — a header and payload. Information about th...

Telnet Definition This is a program that allows you log in to a Unix computer via a text-based interface. If you have an account on a Telnet server, you can access certain resources on the system such your home directory, your e-mail account, FTP files, etc. The downside of Telnet is that, to use it, you need to use Unix commands, which can be a challenge.

WAN Definition Stands for "Wide Area Network." It is similar to a Local Area Network (LAN), but it's a lot bigger. Unlike LANs, WANs are not limited to a single location. Many wide area networks span long distances via telephone lines, fiber optic cables, or satellite links. They can also be composed of smaller LANs that are interconnected. The Internet could be described as the biggest WAN in the world. You could even call the Internet a Super WAN BAM if you wanted to. Or maybe not.

Domain Name Definition A domain name is a unique name that identifies a website. For example, the domain name of the Tech Terms Computer Dictionary is "techterms.com." Each website has a domain name that serves as an address, which is used to access the website. Whenever you visit a website, the domain name appears in the address bar of the web browser. Some domain names are preceded by "www" (which is not part of the domain name), while others omit the "www" prefix. All domain names have a dom...

VPN Definition Stands for "Virtual Private Network" (not a successor to the UPN television network). VPN is a network term that most computer users don't need to know, but at least you can impress your friends by talking about it. A virtual private network is "tunneled" through a wide area network WAN such as the Internet. This means the network does not have to be located in one physical location like a LAN. However, by using encryption and other security measures, a VPN can scramble all the da...

Mail Server Definition A mail server (or email server) is a computer system that sends and receives email. In many cases, web servers and mail servers are combined in a single machine. However, large ISPs and public email services (such as Gmail and Hotmail) may use dedicated hardware for sending and receiving email. In order for a computer system to function as a mail server, it must include mail server software. This software allows the system administrator to create and manage email accounts...