The Tennis Court
The Right Service Box is sometimes called the "Deuce Court" and the Left Service Box is sometimes called the "Ad Court." The reason for this is that when the score is "Deuce," the point is always started with a serve to the right service box. Likewise for a score of "Advantage" (or "Ad") the points begins with a serve to the left service box.
A common misconception is that during doubles play, the Service Line should extend through the Doubles Alley to the Doubles Sideline. However, all serves (regardless of whether a singles match or doubles match is being played) must land in the Right or Left Service Boxes as marked on the court. In other words, there is no imaginary extension of the Service Line through the Doubles Alley to make the service boxes wider for doubles matches.