ATP World Tour 500 series
The ATP World Tour 500 series (previously known as the ATP Championship Series and ATP International Series Gold) is the fourth highest tier of men's tennis tournament after the four Grand Slam tournaments, ATP World Tour Finals, and the ATP World Tour Masters 1000.
The series includes 13 tournaments, with 500 rankings points awarded for the events' singles champions – which accounts for the name of the series. Tournaments have various draws of 32 and 48 for singles and 16 and 24 for doubles. It is mandatory for leading players to enter at least four 500 events, including at least one after the US Open; if they play fewer than four, or fail to play in one after the US Open they get a "zero" score towards their world ranking for each one short.
Roger Federer and Rafael Nadal hold the record for most titles apiece, at 17, while Daniel Nestor holds the record for most doubles titles won with 20.
1990.-1999.
2000.-2008.
2009-current
The following points are awarded to a player who reaches a round of a World Tour 500 event.
Singles
Doubles
...
Wikipedia