In the Internet, each website has its own unique website, which consists of protocol, domain name and port number. Port numbers usually refer to programs or services running on the server. For example, the HTTP service uses port 80 and the HTTPS service uses port 443. The website can respond to the user's request through the program or service pointed by the port number. Therefore, the port number after the URL refers to which services or programs users can access the website.

Generally speaking, users don't need to care what the port number is for websites that use standard port numbers. However, for websites that need custom port numbers, users need to manually enter the port numbers to access them. So how do you query the port number after URL? The common way is to use network tools, such as telnet and curl. These tools can visit the website and get the port number by sending a request to the domain name or IP of the website.

The port number after URL plays a vital role in the normal operation of the Internet. Through the allocation and use of port numbers, the server can distinguish different applications and services, thus realizing the functions of concurrent connection, concurrent communication, distinguishing users and services, load balancing and security management, and ensuring the efficiency, stability and security of the Internet. Therefore, when developing and using Internet applications, the selection, allocation and management of port numbers are very important.