Simple Rules

A badminton match comprises the best of three games. A coin is tossed before the first game, and the winner of the toss may serve first or pick an end of the court(we hit a shuttle up into the air and whoever it points to has won the toss). In the new Rally Point scoring format that just recently adopted and used for major tournaments, the winning team needs 21 points to win the match.

The Court

Court Dimension: 44ft x 22ft (double) / 44ft x 17ft (single)
Net Height: 5ft 1in on the sides / 5ft on the center of court

A rally is won when a shuttle is hit over the net and onto the floor of the opponent's court.
A rally is lost if the shuttle is hit into the net, or over the net but outside of the opponent's court. A rally is also lost if the shuttle touches the player's clothing or body, or if it is hit before it crosses over the net.
The service courts are slightly different for singles and doubles. A shuttle on the line is "in". The server and receiver stand in the diagonally opposite service courts (always right hand at the start of the game) but therefore players may move anywhere on their side of the net. The server must obey laws designed to force underhand delivery of the serve, and the receiver must stand still until the service is struck.
Matches comprise of the best of three games. Each game starts at 0-0 (traditionally called "love-all").If the serving side wins a rally, it scores a point, and serves again but from the alternate service court. If the receiving side wins the rally then they score a point and the service passes to the next player in turn. In singles, this is the opponent: in double it's the player on the correct side of the court depending on the score, even the player on the right serves and uneven the player on the left.
In men's singles and doubles events, 21 points wins a game.