"Purple belt" is a ranking in the martial art of Brazilian jiu-jitsu. Under the adult ranking system promulgated by the International Brazilian Jiu-Jitsu Federation (IBJJF), the purple belt is the third rank up from the bottom (above white belt and blue belt), and a purple belt holder is considered an "intermediate" practitioner of the art.
The IBJJF requires that the practitioner be at least 16 years old and have held a blue belt for a minimum of two years before becoming eligible to wear the purple belt. Given that the 16-year age limit is also in place for earning a blue belt, there are almost no purple belt holders under 18 years of age. A purple belt holder must wait at least 1.5 years before becoming a brown belt.