Several tournaments are held each week as players win prize money and earn ranking points.
In fact, they are obliged to appear in certain of the most prestigious tournaments and in a certain number of these during the year or face being penalized by the tour.
A typical tournament in any tier main draw for singles consists of 32 entrants, while the ATP 1000 events feature 58.
Grand slam tournament play is unique in that, for men, matches are best three of five sets, and that both female and male players do not play singles (or doubles) matches in consecutive days, barring inclement weather or other unforeseen scheduling issues.
The fields are expanded as one hundred twenty-eight singles players and 64 doubles teams are featured in the main draws.
Challenger tournaments were begun in 1978 and initially were separate events that did not comprise a unified tour.
Over time these one-week events replaced satellite tournaments, a mini-circuit typically held over a four-week period at one location.