Idril was the daughter of Turgon of Gondolin. She was also named Celebrindal - "silver foot". She became the wife of Tuor, and thus became one of only three elves ever to marry a mortal man. Their son was named Eärendil.

The family escaped from Gondolin during its fall, and came eventually to Arvernien in the south of Beleriand - near the delta of the Sirion. There they lived until Tuor became old, and then both he and Idril set sail on board the ship Eärámë, journeying to the West.
Encyclopedia entry originally written by atalante_star