Piece of Heart

Pieces of Heart can be found all over Zelda games. The amount to collect is usually four, but in Twilight Princess it was five, so the amount can vary. Collecting the correct amount rewards Link with a Heart Container. Each game has different amounts. Some have 20, some have 52. They are not that rare, though some of them take a long time to do, such as the 50 Gold Skulltula tokens required to get one of the heart pieces in Ocarina of Time.