The default TCP port number for HTTP is 80.
When a browser connects to a URL beginning with http:// and no explicit port is supplied, it normally opens a TCP connection to port 80. HTTP then carries requests and responses between the client and web server over that connection, though modern HTTP versions can also use other transport arrangements.
Port numbers identify services at the transport layer. Assigning port 80 to HTTP gave web software a standard destination, so users could type ordinary web addresses without adding a number such as :80. The port is a convention recorded in the Internet’s service-name and port-number registries, not a technical requirement that every HTTP server must follow.
A common mix-up is 443, the conventional port for HTTPS. HTTPS is HTTP protected by TLS, so secure web addresses beginning with https:// normally use port 443. Other familiar ports have different traditional roles: 25 is associated with SMTP mail transfer, while 21 is used by FTP control connections.