why is port 80 most widely used code example

Example: what is port 80 used for

Port 80 is one of the most commonly used port numbers in the
Transmission Control Protocol (TCP) suite. Any Web/HTTP client,
such as a Web browser, uses port 80 to send and receive requested
Web pages from a HTTP server. It manages all HTTP-based requests
that originate from a computer, regardless of the number of requests
and initiating Web clients. Similarly, the HTTP server responds to
all requests received at port 80.