Ihy was a young god personifying the jubilation emanating from the sacred rattle.
The name of Ihy was interpreted by the Egyptians as "sistrum-player" which was the raison d'etre of this god. The sistrum was a cultic musical instrument used primarily (but not exclusively) in the worship of Hathor, mother of Ihy. At Dendera temple Ihy is the child of the union of Hathor and Horus and is depicted as a naked young boy wearing the sidelock of youth and with his finger to his mouth. He can hold the sacred rattle and necklace (menat).
In the temple complex the birth house or "mammisi" was a sanctuary where the mystery of the conception and birth of the divine child Ihy was celebrated. His name is rarely found outside the confines of Dendera temple, though for example, we occasionally find it in spells of the Coffin Texts or Book of the Dead where he is called "lord of bread...in charge of beer", a possible reference to the celebrations of Dendera deliberately requiring a state of intoxication on the part of the acolyte in order to communicate with Hathor.