Info Tech Guide

Packet is a small amount of computer data sent over a network. Any time you receive data from the Internet, it comes to your computer in the form of many little packets. Each packet contains the address of its origin and destination, and information that connects it to the related packets being sent.

The process of sending and receiving packets is known as "packet-switching." Packets from many different locations can be sent on the same lines and be sorted and directed to different routes by various computers along the way. It works a lot like the post office, except billions of packets are transferred each day, and most packets take less than a few seconds to reach their destination.

A packet-switching scheme is an efficient way to handle transmissions on a connectionless network such as the Internet. An alternative scheme, circuit-switched, is used for networks allocated for voice connections.

In circuit-switching, lines in the network are shared among many users as with packet-switching, but each connection requires the dedication of a particular path for the duration of the connection.

A packet consists of two kinds of data: control information and user data (also known as payload). The control information provides data the network needs to deliver the user data. Typically, control information is found in packet headers and trailers, with user data in between.

Different communications protocols use different conventions for distinguishing between the elements and for formatting the data. In Binary Synchronous Transmission, the packet is formatted in 8-bit bytes, and special characters are used to delimit the different elements.

Other protocols, like Ethernet, establish the start of the header and data elements by their location relative to the start of the packet. Some protocols format the information at a bit level instead of a byte level.