Foundation piles are where you build each suit from Ace to Google solitaire (https://googlsolitaire.com/) King, and using them efficiently is key to winning. Only move cards to the foundation when it doesn't block important moves in the tableau. Focus on uncovering hidden cards before sending too many to the foundation. Plan the order carefully, especially with sequences that might require temporary moves. Efficient use of foundation piles helps keep the game organized and increases your chances of completing all suits successfully.