What is a Foundation in Solitaire?

Foundation
The four piles (one for each suit) where you build cards in ascending order from Ace to King. Moving all 52 cards to the foundations wins the game.

Foundation Rules

Building the foundation correctly is how you win Solitaire:

Example

You find the Ace of Hearts. Move it to an empty foundation. Now you can place the 2 of Hearts on it, then the 3 of Hearts, and so on until you reach the King of Hearts.

Foundation Strategy

When should you move cards to the foundation?

Foundation Variants

Some Solitaire games have different foundation rules: