Understanding the Transfer Control Protocol (TCP)

What is TCP?

Transfer Control Protocol (TCP) is a reliable, connection-oriented protocol commonly used to transmit data across the internet. It works in conjunction with the Internet Protocol (IP) to provide a communication service between two hosts. TCP enables two-way communication by verifying data packets are successfully delivered and reassembling them in the correct order. This makes sure that data is transmitted reliably and efficiently between two computers.

How Does TCP Work?

After two computers have established a connection over the Internet, TCP takes over and starts to communicate. Data is broken down into multiple packets and sent over the connection. The packets include a header that contains information about the sender, receiver, and the size of the packet. When the receiving computer receives the packet, it checks to make sure the packet is complete and that it matches the sender’s address. If everything is in order, the computer sends an acknowledgment back to the sender. If the sending computer does not receive an acknowledgment, it will resend the packet until it is received.

Security With TCP

TCP provides a secure connection between two computers by authenticating each of the computers. This is done through a three-way handshake which is initiated when one computer sends a request to establish a connection (the SYN flag). The receiving computer responds with its own SYN flag along with an acknowledgment (the ACK flag). The sending computer completes the handshake by acknowledging the receiving computer’s response. This ensures each computer is who they say they are, providing a more secure connection than UDP.

TCP in Action

TCP is used in many applications that require a reliable connection, such as web browsing, email, instant messaging, file sharing, and audio/video streaming. You may not even realize you are using TCP, but it is running in the background making sure your data is sent and received safely and quickly.