The "Start" button made its debut in Windows 95.

Windows 95 (originally code-named Chicago) is a hybrid 16-bit/32-bit graphical operating system released on August 24, 1995 by the Microsoft Corporation.

Windows 95 is a direct descendant of Microsoft's formerly separate MS-DOS and Windows products, the first in that line without any support for older, 16-bit x86 processors, thus requiring an Intel 80386 processor, or a compatible faster one, running in protected mode. It featured significant improvements to the GUI and underlying workings, and was the first Windows product to be tied to a particular version of DOS (Microsoft's DOS 7.0). In this way, Microsoft were able to leverage the dominant position Windows 3.1x had established in the GUI market to ensure that no non-Microsoft product would be able to provide the underlying operating system services. Windows 95, in other words, was a dual-role product. It brought significantly greater power and usability to the desktop GUI, and also ended competition in the desktop operating system market. (While it was technically possible to run the Windows 95 GUI on top of DR-DOS - and probably PC-DOS too - this did not emerge in court until some years later, by which time the other major players in the DOS market were effectively out of business.) In the marketplace, Windows 95 was an unqualified success, and within a year or two of its release had become the most successful operating system ever made.

Windows 95 was released with great fanfare, including a commercial featuring the Rolling Stones song Start Me Up (a reference to the Start button). Microsoft's PR campaign featured stories of people queuing outside stores to get a copy, and there were tales of people without computers buying the software on hype alone, not even knowing what Windows was.

The release of Windows 95 coincided with a general movement of computing into the mainstream, largely fueled by a dramatic drop in hardware prices, in particular, by the end of Intel's long-held near-monopoly on CPU production with the entry of fast, low-cost parts from AMD and Cyrix.

Windows 95 marked the introduction of the "Start" button and taskbar to the desktop PC, which have remained staple features of all subsequent versions of Windows.

Later editions of Windows 95 (OSR 2, OSR 2.1, OSR 2.5) came with Internet Explorer 3, then Internet Explorer 4 preinstalled. Internet Explorer 4 introduced several changes to some aspects of the GUI when it was integrated into the operating system. Internet Explorer was then used to render the desktop and window contents using HTML. This was a focal point in Microsoft's antitrust lawsuit, as an integrated Explorer edged out competitor Netscape's product.

Windows 95 has been succeeded by Windows 98, Windows 98SE, Windows ME, Windows 2000 and Windows XP. The Windows NT-based kernel used in Windows 2000 and Windows XP has shown itself to be much more robust, and more powerful than its predecessor in Windows 95, Windows 98, and Windows ME. As a result, those versions of Windows are being phased out. As of December 31, 2002, Microsoft ended its support for Windows 95.

See also: History of Microsoft Windows, Blue screen of death.