Back in early 90's the browser wars reduced the choice to two products: Netscape Navigator 4.7 and Internet Explorer 4.0.
Developers had to write code for one or another. Most websites displayed the notice "Optimised for..."
The web evolved, new products emerged. The Mozilla Foundation split Netscape Communicator into Firefox and Thunderbird, opened the architecture for plugins and created a large community of open source developers. Firefox gained momentum. Many corporations adopted it. Speed, security and adherence to standards were the main factors for mass adoption. Internet Explorer was still very proprietary.
WebKit, an open source project underpinning Safari and Chrome (among others) set new standards. Google poured vast resources to make it a development platform where speed, flexibility and security were the focal points. The Chromebooks run a minimal operating system (Chromium, build on Linux Standard Base) to load Chrome. The browser is the desktop, eliminating the need of constant maintenance.
As of September 2013 Internet Explorer accounts for 12.1% of the browser market, Firefox27.8%, Chrome 53.2%, Safari 3.9 % and Opera 1.7%. There is a clear trend of Chrome growing at expense of other browsers loosing ground.