The Association of Tennis Professionals (ATP) was formed in 1972 to protect the interests of male professional Tennis players. (Female players formed the Women's Tennis Association the year after.)
In 1990, the association became the organizer of the principal worldwide tennis tour, thereafter known as the ATP Tour.
The ATP Tour at present has five categories of tennis tournaments belonging to its tour:
1. Tennis Masters Cup (jointly with ITF)
2. ATP Masters Series Tournaments
3. International Series Gold Tournaments
4. International Series Tournaments
5. Challenger Tournaments
In the history of ATP ranking it was Pete Sampras who stood for a long time as World Number 1. He stood at the rank for 286 weeks. Jimmy Connors is the second best with 268 weeks. Current World Number 1 in ATP rankings is Roger Federer with 162 weeks.
The Women's Tennis Association, is also known as the WTA Tour, and is to women's tennis what the ATP is to men's tennis. In 2005 the WTA changed its name into The Sony Ericsson WTA Tour.
The Women's Tennis Association was begun in
The WTA divides the main women's tournaments into several tiers:
1. Grand Slam Events
2. Season-ending championships (Sony Ericsson Championships): with Three Million Dollars ($3,000,000) prize money.
3. Tier tournaments:
- Tier I (minimum prize money of $1,340,000): There are ten (10) Tier I Tournaments.
- Tier II (minimum prize money of $600,000): There are sixteen (16) Tier II Tournaments.
- Tier III (minimum prize money of $175,000): There are seventeen (17) Tournaments in this Tier.
- Tier IV (minimum prize money of $145,000): There are twelve (12) Tournaments in this Tier.
Steffi Graf was the all time great in WTA rankings with 377 weeks of standing, followed by Martina Navratilova with 331 weeks. The current World Number 1 is Maria Sharapova with 12 weeks of standing.