Network ports provide logical endpoints for communication between applications and devices across TCP/IP networks. Operating from 0 to 65535, ports are divided into well-known (0-1023), registered (1024-49151), and dynamic/ephemeral (49152-65535) ranges, each serving distinct purposes in network architecture. Understanding port assignments, security implications, and service mappings is fundamental to network administration, security hardening, and troubleshooting — ports represent both entry points for legitimate services and potential attack vectors if misconfigured. Port numbers combine with IP addresses to form unique socket identifiers, enabling multiple concurrent network conversations on a single host, making them the foundation of modern networked applications from web browsers to microservices.