What is Super Saiya-jin's?

In the TV series 'Dragonball Z' a Super Saiya-jin is a member of the Saiyan race who has achieved a new level of power. Characterised by the person's hair turning gold/yellow and spiking up, also their power increases many times over. The Saiyan must be pure of heart to turn Super Saiya-jin (SSJ)

Demi Saiya-jin (Gohan, Trunks and Goten) turn Super Saiya-jin more easily.