Short for Transmission Control Protocol, TCP is a standard that dictates how to establish and maintain a connection through which two programs may exchange data. Invented in 1978 and driven by Bob Kahn and Vint Cerf, TCP is a core component in the TCP/IP protocol, which dictates how information is sent over the Internet.
How does it work?
TCP's job is to break down messages or files into smaller pieces (called packets) that are then sent over the Internet. These packets are then received by another TCP layer that then reassembles the data into a complete file or message. TCP is also responsible for error-checking that data stream to ensure the delivery of the data; if an error is found TCP retransmits the packet(s).