Port Number Protocol Common Service 80 TCP HTTP (Web Traffic) 443 TCP HTTPS (Secure Web Traffic) 25 TCP SMTP (Email Sending) 110 TCP POP3 (Email Retrieval) 22 TCP SSH (Secure Shell) 21 TCP FTP (File Transfer) How Ports Enable Specific Applications When you visit a website, your browser uses port 80 or 443 to request the page from the hosting server. For example, a company might close port 22 to the public internet to prevent brute force attacks on their SSH service.
How Ports Organize Network Traffic and Manage Data Flow
Firewalls use port numbers to allow or block traffic, acting as the first line of defense against unauthorized access. Understanding what are ports used for is essential for configuring firewalls, troubleshooting connectivity issues, and optimizing network performance.
Understanding this distinction helps explain how networks handle millions of simultaneous connections without congestion. Data packets are delivered to the building (IP address) and then directed to the correct resident (port number) inside.
How Ports Organize Network Traffic and Direct Data to Applications
Below is a table outlining the most common services and their associated default ports. Troubleshooting with Port Knowledge.
More About What are ports used for
Looking at What are ports used for from another angle can help expand the discussion and give readers a second clear paragraph under the same section.
More perspective on What are ports used for can make the topic easier to follow by connecting earlier points with a few simple takeaways.
