Web servers are special computers that are constantly connected to the internet, and are optimized to send web pages out to people who request them. Big companies have their own servers. Smaller companies (or individuals) can get access to a web server through web hosting services (i.e: GoDaddy)
Web servers are equipped with a server software (i.e: Apache) which tells the machine how to retrieve data and how to fulfill requests.
To organize the data stored within it, the server also uses a type of software called CMS (Content Management System.) (Another type of CMS is used to build the content of a website – see ‘Web Development’ section.)
Any computer can be turned into a Web server by installing server & database software, a robust OS and connecting the machine to high speed internet.
– Anna Pinkas