The ATP 500 tournaments (previously known as the ATP World Tour 500 tournaments, ATP International Series Gold, and ATP Championship Series) are the fourth highest tier of annual men's tennis tournament after the four Grand Slam tournaments, ATP Finals, and the ATP Masters 1000.The series includes 13 tournaments, with 500 ranking points awarded for the events' singles champions – which ...
https://en.wikipedia.org/wiki/ATP_500_tournaments