The term “web server” has two meanings. One is the physical (or virtual) server than contains the website’s files and such.
The other, and the one this page is about, is the service that accepts HTTP requests from a browser, and responds with the appropriate files such that the browser can display the webpage it requested.
There are two main web server services: Nginx and Apache HTTP Server.
Nginx is simpler to configure and is becoming the default choice, and is therefore the one I use. It can also be used as a reverse proxy to allow for one server to host multiple websites – see Proxies for more.