Zelda's Lullaby

Zelda's Lullaby is a recurring song in the Legend of Zelda series, and Ocarina of Time. It is a six-note song played on the Ocarinas, taught to Link by Princess Zelda.

In-game
Link learns the song after sneaking into the Castle and speaking with Zelda. Zelda's nursemaid, Impa, teaches it to him on his Fairy Ocarina. The song can only be learned by members of the Royal Family, according to Impa, so Link uses it to prove his connection to the family. The song is a lullaby for the young Princess Zelda, and playing it solves a variety of puzzles throughout the game. At the end of the game, Zelda sends Link back to the past by playing this mysterious song.

Trivia

 * This song is thought to be the theme song of Princess Zelda.
 * The mark that signals Link to use this song is a Triforce.
 * In Majora's Mask, the "sequel" to Ocarina, Princess Zelda appears only in a flashback, but notes to the song are on some walls, and when played, Rupees appear. Since there is no cutscene teaching Link the song, like all other songs, Zelda's Lullaby can be thought of as a "secret song" in Majora.