Linux Administration Cookbook

Installing and understanding a web server

A web server is the component you're interacting with directly when you go to a website. It traditionally listens on port  80 (for Hypertext Transfer Protocol (HTTP)) or  443 (for Hypertext Transfer Protocol Secure (HTTPS)). 

When you type a URL into your browser, these ports are generally hidden unless explicitly defined; for example, hitting https://duckduckgo.com in Chrome or Firefox will load the website, but it won't tell you that it's connecting on port 443. In a similar fashion, if you go to https://duckduckgo.com:443, the exact same page should load.

Also, if you try to go to port 80 using HTTPS (https://duckduckgo.com:80/), you will generally get an error saying the site can't provide a secure ...