I love watching professional tennis on TV.
I agree as the players can get agressive at times, sending the ball in bounds without a valid return by the opponent
Yes it's very exciting and entertaining.
The players have to strategically hit the ball as to not allow an inbound return. 
I've tried to play before, it's not easy!
The tennis point system is interesting. The player unable to return the ball scores zero, the other player gets a point.
Yes and then doesn't it go to 15 then 30?
19th century, in fact, the term "tennis" referred to real tennis, not lawn tennis.
The rules of modern tennis have changed little since the 1890s. Two exceptions are that from 1908 to 1961 the server had to keep one foot on the ground at all times, and the adoption of the tiebreak in the 1970s. A recent addition to professional tennis has been the adoption of electronic review technology coupled with a point-challenge system, which allows a player to contest the line call of a point,
sound of the ball leaving the grunter's racquet and prevented an experienced opponent from using that clue as to force and spin to address his or her reception of the ball and the return stroke. Another former player, Chris Evert, stopped short of labelling it as cheating but said: "I wouldn't go that far [to say it's cheating] but I think the grunts are getting louder and more shrill now with the current players".
Some tennis players have defended grunting. Michelle Larcher de Brito, who