“A serve is 50 percent of the points you serve or your return in a match,” said Anthony Evrard, PTR-certified, former professional Belgium tennis player. “Unlike a forehand or backhand shot that comes from the other side of the net, a serve, like a free throw in basketball, is the only shot you have 100 percent control over.
https://www.nike.com/a/how-to-serve-in-tennis