Table tennis is a sport that requires a complex set of rules to be followed. Most casual players are unaware of the regulations and serve illegally. To help you resolve disputes and understand the essential rules of table tennis, we have summarized the regulations from USA Table Tennis. The lower part of the net, along its entire length, must be as close as possible to the playing surface and the ends of the net must be as close as possible to the support posts.
A game is played with 11 points and must be won by two points. Usually, one game is the best of three out of five games. If you're not very strict with the rules, you can play illegal serves in table tennis. During a rally, if the ball hits the net but bounces off the opponent's side of the table, the rally continues.
However, if the ball hits the net and doesn't reach the other half of the table, the receiver automatically receives a point. A return (not a service) that hits the network (or any part of it) and lands on the opposite side of the table is acceptable. During a serve, if the ball hits the net but still bounces off the opponent's side of the table, it is considered a let (meaning you have to play it again). During intervals between games, players must remain less than 3 meters from the playing area under the supervision of a referee.
Each player alternately serves two balls at a time until either the end of the game or until the score reaches 10-10.