The Association of Tennis Professionals (ATP) and the Women's Tennis Association (WTA) are two of the main governing bodies in the professional tennis, along with the International Tennis Federation (ITF).
The ATP was founded back in 1972 and currently oversees over 60 tournaments in more than 30 countries, and similar applies to the WTA, which was founded a year later, in 1973, and currently oversees more than 50 tournaments in close to 30 countries.
One common misconception is that the ATP and the WTA co-organize the Grand Slam tournaments - Australian Open, Roland Garros, Wimbledon, and US Open. This is not true, as it's the ITF that oversees those tournaments.
On top of that, the ITF is also in charge of the lower-tier tournaments, often called the Futures, and it has its own ITF Tour. On top of that, the ITF oversees also the World Tennis Tours of Juniors.
Both ATP and WTA also have their own representation, whether in management or in the Player Councils. Still, there is an association that represents players from both Tours, but it's an independent association launched in 2019 by Novak Djokovic, called the Professional Tennis Players Association (PTPA).
While both ATP and WTA tours have their separate calendars, there are still plenty of tournaments when the Tours cooperate. Some of the events are held in simultaneous weeks, while others just happen to be held in the same city under different organizations.
There are many other tournaments that are held for both ATP and WTA players, but the inclusion of these tournaments often changes in the tennis calendars.
