Typically, after a successful junior or college career, players enter professional competition at the Futures level, governed by the ITF, where each ITF Men's Circuit tournament offers prize money of either $10,000 or $15,000. In $10,000 events, the main draw has 32 players, and the qualifying has 128. $15,000 events keep 32 in the main draw but limit the qualifying to 64. In either case, a player earns ATP ranking points by reaching at least the round of 16 (winning at least one match in the main draw).
The next step up from Futures is the Challengers level, where each event requires a minimum ranking for entry, except for those few lucky enough to get a wild card. Governed by the ATP, Challengers events generally feature players ranked between 71 and 400 vying for a share of $50,000-$100,000 per tournament. Both the main and the qualifying draws have 32 players. Challengers events are one step below ATP Tour events, and many pros play in both.
ATP Tour events are organized into three levels, each named for the number of ranking points awarded to the winner: ATP World Tour 250, ATP World Tour 500, and ATP World Tour Masters 1000. Prize money for each of the 39 ATP World Tour 250 events averages around $500,000; the 11 ATP World Tour 500 events average roughly $1.5 million, and the 9 Masters events offer $3-5 million. Main draw sizes range from 32 for 250 events to 96 for the largest of the Masters events. Along with the season finale, the Barclays ATP World Tour Finals, Masters events are the highest level of competition governed by the ATP.
At the pinnacle of professional tennis are the Grand Slams: the Australian Open, Roland Garros (the French Open), Wimbledon, and the US Open, all governed by the ITF. The careers of great players are usually remembered almost entirely for their Grand Slam records. In addition to a place in history, a Grand Slam winner earns 2000 ranking points and at least a $1 million share of an average $20 million prize money. With main draws of 128 players, each match decided by the best of five sets, and spans of two weeks, Grand Slam tournaments stand apart, and millions of fans who barely pay attention to the rest of the tennis calendar eagerly await these landmark events.