The Golden Goddesses, Nayru, Din, and Farore created the realm called Hyrule. In this realm, they left behind a Sacred Relic known as the Triforce.
The Triforce is the Ultimate source of Power in the Zelda series and serves as the Balance that weighs the Three Forces: Power, Wisdom and Courage.
Those who possess this Amulet have all their wishes granted; it matters not if their intentions are Good or Evil.
The physical appearance of the Sacred Realm can even be changed by the Triforce-it becomes a reflection of the possessor's heart.
The Triforce consists of three separate triangles: the Triforce of Power, the Triforce of Courage, and the Triforce of Wisdom.