In a TCP/IP network (such as the Internet), it is a number assigned to a type of service. The port number is included in all transmitted packets to link incoming data to the appropriate application. For example, port 80 is the standard port number for HTTP traffic (Web traffic), and port 80 packets are processed by a Web server. Standard port numbers range from 1024 through 49151 (see well-known port).
The software that responds to its port number is said to be "listening" for its packets. More accurately, the term should be "looking" for its packets, because it is comparing numbers, not "listening" to numbers. However, computer terminology has never been known for clarity.
Tags: HTML, Networking, Software