Port

A port is a number (0-65535) that identifies a specific service running on a server. Think of the IP address as the building's street address and the port as the apartment number. Web servers listen on port 80 (HTTP) and 443 (HTTPS). SSH uses port 22. Email uses ports 25, 587, and 993. When you visit https://example.com, your browser connects to port 443 on example.com's IP address. Firewalls control which ports are open (accepting connections) and which are blocked.