Solitaire is a computer card game that is included in Microsoft Windows. It is a version of Klondike.

Microsoft has included the game as part of the Windows operating system since Windows 3.0, starting from 1990. The game was developed in 1989 by then intern Wes Cherry, who famously received no royalties from his work. The card deck itself was designed by Macintosh pioneer Susan Kare.

Microsoft intended Windows Solitaire "to soothe people intimidated by the operating system", and at a time where many users were still unfamiliar with graphical user interfaces, it proved useful in familiarizing them with the use of a mouse, such as the drag-and-drop technique required for moving cards.

Lost business productivity by employees playing Solitaire has become a common concern since it became standard on Microsoft Windows. In 2006, a New York City worker was fired after Mayor Michael Bloomberg saw the Solitaire game on the man's office computer.

Since Windows 3.0, Solitaire allows selecting the design on the back of the cards, choosing whether one or three cards are drawn from the deck at a time, switching between Vegas scoring and Standard scoring, and disabling scoring entirely. The game can also be timed for additional points if the game is won. There is a cheat that will allow drawing one card at a time when 'draw three' is set.

Solitaire is any tabletop game which one can play by oneself or with other people. In the USA, it may refer to any card game played by oneself; the British use the term Patience to refer to solitaire with cards. The term "solitaire" is also used for single-player games of concentration and skill using a set layout of tiles, pegs or stones rather than cards. These games include Peg solitaire and Mahjong solitaire. Most solitaire games function as a puzzle which, due to a different starting position, may (or may not) be solved in a different fashion each time.

There are a number of different types of solitaire game. These include:

Microsoft Windows is a series of graphical interface operating systems developed, marketed, and sold by Microsoft.

Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Microsoft Windows came to dominate the world's personal computer market, overtaking Mac OS, which had been introduced in 1984.

The most recent client version of Windows is Windows 7; the most recent server version is Windows Server 2008 R2; the most recent mobile version is Windows Phone 7.5.The most recent unstable release is Windows 8.

The term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are generally categorized as follows:

The history of Windows dates back to September 1981, when Chase Bishop, a computer scientist, designed the first model of an electronic device and project "Interface Manager" was started. It was announced in November 1983 (after the Apple Lisa, but before the Macintosh) under the name "Windows", but Windows 1.0 was not released until November 1985. The shell of Windows 1.0 was a program known as the MS-DOS Executive. Other supplied programs were Calculator, Calendar, Cardfile, Clipboard viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal, and Write. Windows 1.0 did not allow overlapping windows. Instead all windows were tiled. Only dialog boxes could appear over other windows.