Ports are numerical labels used in networking to identify specific types of network service. They enable a single device, with a single IP address, to run multiple simultaneous communication sessions with other devices.
Ports are numbered, ranging from 0 to 65535. Commonly-used services have standardised port numbers, known as “well-known ports” (ranging from 0 to 1023), such as HTTP (80), HTTPS (443), FTP (21), SSH (22), and SMTP (25). Ports ranging from 1024 to 49151 are “registered ports” designated for specific services, and those from 49152 to 65535 are considered “dynamic” or “private ports,” generally used for client-side applications. Network administrators can configure servers to listen on specific ports and can set firewall rules to control traffic based on port numbers, enhancing network security and management.