To have a web site visible over the internet, you need a web server. A web server is an application that manipulate html files. The web server is responsible to accept requests from the users, through a web browser. When you, as a user, type an URL (Uniform Resources Locator) in the browser you are making a request of a html file. This request will arrive at the server where the site is hosted. The web server understands your request and analyze it. As a result the web server will send to your browser requested page. The communication between web server and your browser is made via a protocol named HTTP.
The most popular web server on the internet is Apache. Certainly we will use it, too.
We choosed Apache and not another solution for the following reasons:
Apache is free.
Apache is open source
Apache is a web server that works fine with UNIX Windows, and other platforms.