Ports

After a bit of research, anyone interested in computer networking will run into a simple but fairly obscure topic: ports. Of course I am not talking about sea ports, but they can be a helpful analogy to understand what a networking port is. While most internet users are familiar with what an IP address is, and maybe with what a mac address is; ports on the other hand, while commonly talked about, can be more difficult to understand. One reason of why that could be is simply bad nomenclature. After all, computer ports are usually used for physical connections, for example: USB port, HDMI port, thunderbolt port. Networking ports on the other hand are more virtual. We can use a more familiar analogy: sea ports. A ship that arrives at a port can’t just dump all of it’s containers at a random location, instead, it has to stop at a specific dock where it can unload the shipping containers. A networking port is just like that dock: a place at which messages are sent to a specific application.

People familiar with IP addresses understand that an IP address is the address of one’s computer. While this is a vast simplification, it can help in this demonstration. Just like the internet is vast web of interconnected computers, a computer is its own vast web of applications, and simply sending a message to one’s computer won’t suffice. You have to send it to a specific app the computer is using. That is where ports come in: they tell what type of application should receive the message. For example, the Simple Mail Transfer Protocol, which is the protocol behind email, uses port 25, while https uses port 443. This allows for emails to go to the email app and the websites you visit to the web browser. This is still a simplification, as many different applications can use one port. That, however, is a completely different topic. What is important to remember, is that a port is a small part of a much more complex system that ensures seamless delivery of your emails, text messages, and Youtube videos.