Port numbers are an essential part of the Internet’s infrastructure. Without them, computers and other devices would not be able to communicate with each other or access resources on the web. A port number is a numerical label assigned to each end-point of communication in a networked system, allowing different applications and services to identify which traffic should be routed where. The most common use for port numbers is in Transmission Control Protocol (TCP) connections, though they can also be used with User Datagram Protocol (UDP).
Port numbers range from 0 through 65535, although only ports 1 through 1023 are designated as “well-known” ports with specific uses within certain protocols, such as HTTP or FTP. Commonly used, well-known ports include 80 for HTTP and 21 for FTP; however, many more may need to be opened depending on what type of application you’re running or the service you want your computer/device connected to. For example, some games will require their unique port number to communicate appropriately across networks without interference from outside sources like firewalls blocking them off entirely due to security concerns.
For two computers/devices using TCP/IP protocol stack technology—the foundation behind all modern internet communications—to successfully connect over a network connection requires both sides to have open corresponding port numbers set up correctly between themselves before any data transfer takes place at all – otherwise, it won’t work! It’s essential when setting up these types of systems, that users understand how this works because if something isn’t configured correctly, it could lead to severe problems down the line, including potential security risks if left unchecked by those responsible for managing said systems & networks alike – especially true when dealing with public-facing websites & servers exposed directly online via static IP address assignments instead hidden away safely inside private LANs protected by NAT routers, etc.