To set you straight right off the bat (paddle): don't call table tennis 'ping pong'. At least, not within hearing of anyone who plays the game seriously. Ping pong is in fact a trade name1: Parker Brothers came up with it when they wanted to market the game of table tennis. It can be said that ping pong is actually a different game entirely: one in which every shot is like a serve in table tennis2. Table tennis is, despite its common nickname, a real sport. It's even a discipline in the Olympics.
People whose only experience of table tennis is as a game you play in a bar after drinking about five pints, or in your basement on a lazy Sunday when the TV is broken, have no idea of the amount of skill that is needed to play well. You need much faster reactions than in tennis, and almost as much stamina.
Table tennis is the second most popular ball sport in the world, after soccer. This is mostly due to its huge popularity in East Asia, where it was introduced by British Army officers in the late 1800s. It is the national sport in China, which has traditionally dominated the sport at the international level. It also has a large following in Europe, especially in Sweden and Germany.
Two players stand at opposite ends of a table divided by a net.
The serve must bounce once on the server's side, and once on the receiver's side; thereafter, shots are traded with the ball bouncing only on the receiver's side for each shot made.
Failure to return the ball results in a point being awarded to your opponent.
The first player to gain to 21 points wins.
Doubles is also played; it differs from tennis doubles most significantly in that there is strict rotation between partners in making returns.