ME
EN9-ball rules
The game
9-ball is played with balls 1–9 and the cue ball. Balls are played in numerical order, and the player who legally pockets the 9 wins the rack.
Determining the break
The lag winner decides who breaks first. Alternating break is the standard model.
The rack
Balls are racked in a diamond shape, packed as tightly as possible. The 1-ball is at the apex, the 9-ball in the centre, the rest placed at random. The 9 sits on the foot spot and the Illegal Break (three-ball) rule applies.
Legal break
The cue ball is placed anywhere behind the head string. If no ball is pocketed, at least four balls must reach a rail or the break is foul.
Push out
If no foul was made on the break, the shooter may call a push out. They must clearly announce it to the referee; the wrong-ball-first and no-rail rules are then suspended. If no foul occurs on the push out, the opponent chooses who shoots next.
Continuing play
If the shooter legally pockets a ball (other than on a push out), they continue. Legally pocketing the 9 on any shot other than a push out wins the rack. Missing or fouling ends the inning; without a foul, the opponent plays from where the cue ball lies.
Spotting balls
If the 9-ball is pocketed on a foul or jumps the table, it is spotted. No other ball is ever spotted.
Standard fouls
A standard foul gives the opponent ball-in-hand. Standard fouls: cue ball off the table; wrong-ball-first contact (must hit the lowest-numbered ball); no ball reaches a rail after contact; no foot on the floor; ball off the table; bad hit on frozen balls; double hit; push shot; balls still moving; cue ball placed wrong; cue left on the table; playing out of turn; slow play.
Serious fouls
Three consecutive fouls cost the rack. For unsportsmanlike behaviour the referee chooses a penalty proportionate to the offence.
Stalemate
On a stalemate, the player who broke that rack breaks again.
This is an informative summary. Official tournaments follow WPA/EPBF rules.