Windows through the ages: the history of the world's most popular OS

Windows 1 (1985) The first version of Windows was intended primarily to be used with the keyboard. A mouse was strictly optional and very few PCs at the time had one. (Microsoft)

Windows 3 (1990) The first commercially successful version of Windows, Windows 3 was initially panned by critics for requiring the use of a mouse. We all know how that went. (Microsoft)

Windows 95 (1995) Windows 95, released a few years later in August of 1995, included a substantially reinvented user experience with features like the Start menu, taskbar, Explorer, and the desktop. (Microsoft)

Windows XP (2001) Windows XP was released to PC manufacturers on August 24, 2001, and represented another important evolution in the Windows user interface, including changes to the Start menu and program manager. (Microsoft)

Windows Vista (2006) In 2006, Windows Vista substantially changed the visual appearance of Windows with the introduction of "Aero," which brought highly-rendered glass, light sources, reflections, and other graphically complex textures in the title bars, taskbar, and other system surfaces. (Microsoft)

Windows 7 (2009) Windows 7 was released in the fall of 2009 and introduced a totally revamped taskbar. (Microsoft)

Windows 8 (2012) The new Windows 8 look and feel exudes "clean and crisp." (Microsoft)

Windows 8: Metro (2012) Metro represents a shift towards touch, emphasizing "live tiles" and apps instead of the classic desktop. (Microsoft)

Windows Phone (2012) New Windows phones, like the Nokia Lumia 800 (pictured) also feature Metro-style live tiles. (Reuters)