A Web Server is a program that uses HTTP to serve the files that form Web pages to users, in response to their requests.
The primary function of a web server is to store, process and deliver web pages to clients. The communication between client and server takes place using the Hypertext Transfer Protocol (HTTP).
Apache Web server is one of the most prevalent web servers. Apache is a web server application that handles incoming and outgoing HTTP traffic.when a user makes a URL request to an Apache server, the Apache server will handle the HTTP request and return the requested Web pages.
An Apache server will handle numerous HTTP requests at a single time. In order to do this, the server has to run on multiple “threads” of execution. The Apache server will create a new thread for each HTTP request that will handle fetching and returning the requested Web page. This allows Apache to serve Web pages to multiple users at the same time.
A popular implementation of the Apache server is the “LAMP” (Linux, Apache, MySQL and PHP/Perl/Python) stack. This configuration packages the Apache server with its Web-serving capabilities with the MySQL database and scripting languages such as PHP in order to serve database content for updated websites such as blogs.