Klondike is a solitaire card game often known purely by the name of 'Solitaire', it is probably the most well known solo card game.

Taking a standard 52-card deck of playing cards (without Jokers), deal one upturned card on the left of your playing area, then six downturned cards. On top of the downturned cards, deal an upturned card on the left-most downturned pile, and downturned cards on the rest until all piles have an upturned card. Your pile should look like the following figure:

             O   O   O   O


+-+ +-+ +-+ +-+ +-+ +-+ +-+
| | +-+ +-+ +-+ +-+ +-+ +-+
+-+ | | +-+ +-+ +-+ +-+ +-+
    +-+ | | +-+ +-+ +-+ +-+
        +-+ | | +-+ +-+ +-+
            +-+ | | +-+ +-+
                +-+ | | +-+
                    +-+ | |
                        +-+                           

The four foundations (represented by O in the figure) are built up by suit from Ace to King, and the tableau piles can be built down by alternate colours, and partial or complete piles can be moved if they are built down by alternate colours also. Any empty piles can be filled with a King or a pile of cards with a King at the top.

There are different ways of dealing the remainder of the deck: some choose to turn three cards at once to the waste, and either allow three passes through the deck or place no limit on passes through the deck; others turn only one over, but only pass through the deck once.

Microsoft has included Klondike as part of the Windows operating system since the 1.x series. Just like GNOME and KDE, who provided corresponding applications (sol and kpat) already since early versions.

It has been reported to be the most commonly played computer game in recent history, possibly ranking higher than even Tetris.

For definitions of the words in italics, see solitaire terminology