The introduction in 2004 of the open-source Mozilla Firefox browser -- ironically an offshoot of the remnants of Netscape, which was sold to and later abandoned by AOL -- changed the game with innovations like tabbed browsing that have now become industry standard. But perhaps even more importantly, Firefox took market share from IE and prompted a new wave of competition in the market, leaving room for new companies to enter.

Microsoft rival and search giant Google even came out with its own browser, Chrome, last year, and is planning a desktop OS of the same name to compete with Windows on low-cost PCs. The Chrome OS is based on the concept of using a browser to access Web-based applications for everyday tasks like e-mail and word processing, another emerging trend that is raising the profile of browser software.