A real house has only a few doors, but an IP address can have 65536 ports! Ports are marked by port numbers, which are only integers from 0 to 65535. It should be noted that the ports are not in one-to-one correspondence. When your computer accesses the WWW server as a client, the WWW server uses "80" port to communicate with your computer, but your computer may use "3457" port. With the above basic knowledge, each protocol has a default port number (which can be changed). "The port number used for HTTP communication is 80, and SSL generally uses port number 443", which is easy to understand. The default port number of http is 80ssl, and the default port number is 443. Of course, these two port numbers can also be changed.