This is a list of common web browsers around.
Internet Explorer is a web browser that comes with Microsoft Windows. During the 90s, IE competed with Netscape Navigator to be the most dominant web browser. Using its monopoly over desktop operating systems microsoft was able make IE the dominant web browser as well. Because of this Microsoft was sued by the US government under antitrust laws.
Mozilla Firefox is a popular web browser based on Netscape Navigator. It's an open source project maintained by Mozilla Corporation. Firefox is customizable with thousands of add-ons and skins. Usually the default web browser in Linux distributions such as Ubuntu.
Some well known Firefox add-ons.
Google Chrome is an open source web browser created by Google. It has made use of many new ideas making it quite different from the other browsers. Each tab is sandboxed by having its own process. This way, crashes are limited to the web page that caused it. Already some of the major browsers have started copying some of these features. The creation of this browser has put a strain on the google/firefox as google is a major financial contributor to the Firefox group. Google Chrome has a built-in DOM inspector, similar to the functionality given by Firebug. Chrome uses the Webkit layout engine.
OS Support Edit
Opera is most notable feature is it's small memory footprint which allows it to be used on platforms where other browsers would not work, such as mobile phones. Many popular features in other browsers originated in Opera, such as tabbed browsing. Opera has an integrated email client. It has been less popular than other browsers as for a long time users were charged to use it when other browsers were free.
Web standards have been created prevent most compatibility problems. However Internet Explorer which is the most popular web browser is the least standards compliant. making matters worse is there is a small population of users that continue to use old versions of Internet Explorer.