How does rally scoring work in badminton and volleyball?

Under rally scoring, a point is awarded on every rally regardless of who served. Under the older side-out systems, only the serving side could score, and winning a rally as receiver merely won you the serve.

The change was made to make match lengths predictable for television. Side-out scoring could produce very long passages where the serve changed hands repeatedly with no points, and matches ran to unpredictable durations.

Badminton moved to rally scoring in 2006. A game is played to 21 points, and must be won by two clear points. If the score reaches 20–20, play continues until one side leads by two — but with a hard cap at 30, so at 29–29 the next point wins. Matches are best of three games.

Volleyball adopted rally scoring in 1999. Sets are played to 25 points, win by two, with no upper cap — a set can theoretically continue indefinitely. Matches are best of five sets, and the deciding fifth set is played to 15, again win by two.

The practical effect in both sports was to raise the value of every rally. Under side-out scoring a receiving error cost nothing on the scoreboard; under rally scoring it costs a point immediately, which rewards consistency and reduces the advantage of a dominant serve.

In volleyball, the side winning a rally also gains the serve and rotates one position clockwise, so scoring and rotation are linked.

Squash made a similar transition, moving from hand-in hand-out scoring to point-a-rally.

One detail specific to badminton: because there is no separate serving rotation as in volleyball, the side winning a rally serves next, and in doubles the serving court alternates according to the server's score being odd or even. That link between score and court position catches new players out more than the scoring itself.