Now I'd like to say a couple of words about doubles formation and the doubles court. When you are serving in doubles, you can essentially serve the entire width of the court, the entire 20 feet wide, but you can only serve to the first service line, which is this line over here. If you serve past this line, for example in this area, this is considered out in doubles.
For singles, however, you can serve the singles width, which is from this mid-line all the way to the first singles line, 17 feet wide. But for singles you can serve the entire length of the court, all 44 feet long.
And in terms of the doubles game, you and your partner have two basic formations. You can have a defensive formation in which both you and your partner are expecting to receive a smash from your opponent. And basically, you are both crouching low with your knees bent ready to return a smash from your opponent.
As opposed to the defensive position, you can also have an offensive position or an attacking position, in which one of the players is in front, ready to smash the shuttle down at the net, while the other player is at the back, also ready to smash the shuttle from the back of the court.
And this is your basic doubles formation.