Definition of a Browser
Merriam-Webster's dictionary defines a web browser as a computer program used for accessing sites or information on a network (as the World Wide Web). This is a simple, yet accurate description. Web browsers come in many different styles, each with their own nuances. However, the main reason a person utilizes a web browser is to view web pages on the Internet, similar to the way you are viewing this article right now.
How a Browser Retrieves a Web Page
The browser application retrieves or fetches code, usually written in HTML (HyperText Markup Language) and/or another language, from a web server, interprets this code, and renders (displays) it as a web page for you to view. In the majority of cases, user interaction is needed to tell the browser what web site or specific web page he or she would like to view. One way this is done is via the browser's address bar.
The web address, or URL (Uniform Resource Locator), that you type into the browser's address bar tells the browser where to obtain a page or pages from. For example, let's say that you typed the following URL into the browser's address bar: http://about.com/compute/.
In this case, you're attempting to reach the Computing & Technology section of About.com. The browser looks at this particular URL in two main sections. The first is the protocol, which in the address shown is "http://". HTTP, which stands for HyperText Transfer Protocol, is the standard protocol used to request and transmit files on the Internet, mostly web pages and their respective components. Since the browser now knows that the protocol is HTTP, it knows how to interpret everything located to the right of the forward slashes. It now looks at "about.com", which tells the browser the location of the web server it needs to retrieve the page or pages from.
Next, once it reaches this web server, it retrieves the index page of the "/compute" directory. Once this page is retrieved by the browser, it is interpreted and rendered in the browser's main window for you to view.
Much More on Web Browsers
Throughout this site, you will find a wealth of information on web browsers, including different styles of browser, tutorials on how to use them for different purposes, security when using a browser, and much more!