What is Threefold Repetition?

Threefold Repetition is a rule in chess that states if the exact same position appears on the board three times, with the same player to move each time, and all other factors being the same (such as castling rights and en passant availability), then the game may be declared a draw. This rule allows a player to claim a draw if they are able to demonstrate that such a condition exists. The repeated positions do not need to occur in succession.