How Tennis works

Points build into games, games into sets, and sets into the match. At each level you must win by two, so no lead is ever quite safe. Point scores use the historic terms rather than plain numbers.

• Points: 15, 30, 40, game — 40–40 is deuce, and you must win two in a row
• Games: first to six, but two clear — 6–5 is not enough
• Tiebreak at 6–6: first to seven points, again by two
• Sets: best of three, or best of five at the men's Grand Slams

Each point begins with a serve, struck from behind the baseline diagonally into the opposite service box. The server gets two attempts; missing both is a double fault and loses the point outright. A serve that clips the net and lands in is replayed as a let.

• Service alternates sides of the centre mark on each point
• Players alternate serving each game
• A serve landing outside the service box is a fault
• Elite servers exceed 200 km/h and win most of their service games

After the serve, the ball must clear the net and land within the opponent's court. It may bounce at most once before being returned, though returning it before it bounces — a volley — is legal from anywhere except on the serve return, and only inside the court.

• A ball touching any part of the line is in
• Hitting the ball twice, or touching the net, loses the point
• The ball may be played after clipping the net during a rally

All courts share the same dimensions, but the surface changes the sport completely. Grass is fast and low, rewarding serves and volleys. Clay is slow and high, rewarding endurance and topspin. Hard courts sit in between. This is why the four Grand Slams, played on three surfaces, are so hard to win in the same year.

• Singles court 8.23 m wide; doubles adds the tramlines to 10.97 m
• Net height 1.07 m at the posts, 0.914 m in the centre
• Grass — Wimbledon; clay — Roland-Garros; hard — Australian and US Opens

Because serving is such an advantage, winning your own service game is the expectation — a 'hold'. Winning a game on the opponent's serve is a 'break', and at professional level a single break is usually enough to decide a set. This asymmetry structures the whole tactical shape of a match.

A chair umpire oversees the match, supported at major events by line judges or, increasingly, by automated line calling. Players may challenge calls using electronic ball tracking, which is accurate to within a few millimetres and has largely ended the sport's most famous arguments.