Web browser

Definition-A browser is an application program that provides a way to look at and interact with all the information on the World Wide Web. The word "browser" seems to have originated prior to the Web as a generic term for user interfaces that let you browse (navigate through and read) text files online.
Technically, a Web browser is a client program that uses HTTP (Hypertext Transfer Protocol) to make requests of Web servers throughout the Internet on behalf of the browser user. Most browsers support e-mail and the File Transfer Protocol (FTP) but a Web browser is not required for those Internet protocols and more specialized client programs are more popular.

The first Web browser, called WorldWideWeb, was created in 1990. That browser's name was changed to Nexus to avoid confusion with the developing information space known as the World Wide Web. The first Web browser with a graphical user interface was Mosaic, which appeared in 1993. Many of the user interface features in Mosaic went into Netscape Navigator. Microsoft followed with its Internet Explorer (IE).

As of September 2006, Internet Explorer is the most commonly used browser, having won the so-called browser wars between IE and Netscape. Other browsers include:

Firefox, which was developed from Mozilla (the open source version of Netscape).
Flock, an open source browser based on Firefox and optimized for Web 2.0 features such as blogging and social bookmarking .
Safari, a browser for Apple computers (at this writing, the third most popular browser).
Lynx, a text-only browser for Unix shell and VMS users.
Opera, a fast and stable browser that's compatible with most relatively operating systems.
Reference:http://searchwindevelopment.techtarget.com/sDefinition/0,,sid8_gci211708,00.html