Association of Tennis Professionals
The Association of Tennis Professionals (ATP) is the governing body of the men's professional tennis circuits – the ATP Tour and the ATP Challenger Tour. It was formed in September 1972 by Donald Dell, Jack Kramer, and Cliff Drysdale to protect the interests of professional tennis players, and Drysdale became the first president.
Source: Wikipedia — Association of Tennis Professionals (CC BY-SA 4.0)