Some people believe that the ancient Egyptians, Greeks, and Romans played different versions of tennis. Drawings and descriptions of any tennis-like games have not been discovered, but a few Arabic words dating from ancient Egyptian times are cited as evidence. The theory goes that the name tennis is derived from the Egyptian town of Tinnis alongside the Nile and the word racquet evolved from the Arabic word for palm of the hand, rahat.
Tennis professionals players spend minimum 5 hours a day training without saying other type of trainments like psycologists and etc. Statistics say that 1 out of 100000 tennis players can live from tennis. If you manage to stay 5 years on the top 100 atp you´ll have a sallary of 1500$ per month, higher you are in the rank higher you´ll have the salary.
Tennis basic rules
Ball can only bounce once, needs to go over the net, needs to bounce inside the court line. Yoy have two serves, if its net it will repeat the serve. Players can´t talk with no one (except the referee and the opponent). The match is to the best of 3 sets and each of the sets to 6 games, but if the playes get to 5-5 it will carry on until 7, if they still get to 6-6 they´ll play a tiebreak until 7 points (except on grand slams the matche will be up to the best of 5 sets).