One important core protocol is Transmission Control Protocol, or TCP. TCP controls communication in an ordered and precise way by using connections, flow control, and verifications. TCP can establish and verify its connections by using a series of packets and acknowledgements sent between the two parties, such as the three-way handshake. TCP can also maintain good flow control by using a sliding window protocol. This protocol numbers the segments in a specific order so that the recipient receives the right number of segments at a time.

Two additional core protocols that are closely related are HTTP and HTTPS. HTTP, which runs on TCP port 80, is in charge of the process of transferring data between a web browser and a web page. This helps the user to connect with the website they are using. HTTPS is similar to HTTP, but HTTPS is much more secure because of its use of encryption. Additionally, HTTPS runs on TCP port 443.