Web Server Introduction
HTTP is a client-server protocol; where a client uses a web browser to request web pages from a web server and the web server respond to the client with requested web page.
You can refer below image to understand client-server web architecture:
The web server receives a request and responds with the content of the web page requested by the client.
Generally, web server run on http and https port (80 and 443), but the user has the preference to change the port as per the requirements.
When we typing URL without port means it will go through http means port 80, and if you mention protocol https, it will use port 443. If you are using a different port, you need to specify the port with URL in the address bar of a browser.