The ‘Server’ is the web application which process web requests from a remote location and send to clients. It runs a scripting language on webserver and generates HTML pages, and send them to client browsers. It provides interface to databases on the server. the connects between the displayed page of client and database server always change.
When databases are needed to access the web application post to web server, and server will process the code. Examples of server side process are user validation, retrieving, saving and navigation to the pages. The disadvantage is that it take lots of time to process a data and send back to client.