A port is a numerical identifier used by a server or application to distinguish between different network services running on the same machine. Ports allow multiple programs to listen for and handle network traffic simultaneously. For example, web servers usually listen on ports 80 or 443, while databases or APIs use other assigned values. Ports form part of a connection alongside IP addresses, helping route packets to the correct process. Firewalls and load balancers often use port rules to control access. Ports are essential to the structure of internet communication.
how it works
When a server binds to a port, it tells the operating system to direct incoming packets with that port number to the associated process. Clients specify a destination port when making a request, ensuring it reaches the correct service. Ports are divided into ranges: well known, registered, and dynamic. Misconfigured ports can lead to application failures or security vulnerabilities. Understanding ports is crucial when deploying APIs, configuring NAT, or debugging connection issues.