Who is Turgon from The Silmarillion and what is their importance?

Turgon is the second son of Fingolfin. He dwells at Vinyamar, or New Dwelling, in Nevrast until Ulmo directs him to build Gondolin in a hidden vale in the mountains. Turgon rules Gondolin until he is killed when Maeglin betrays the city to Morgoth. His daughter is Idril and his grandson is Earendil. Turgon raises his sister's son, Maeglin, after Aredhel's death.