Illegal Shots (or Fouls)
There are a few different kinds of fouls that are commonly committed:
Fouls of the general rules
Fouls on the rules of a specific game (like eight ball or nine ball)
Fouls of rule variations implemented by players before a match
There is another category of foul that is subjective. It's called “unsportsman-like conduct.” This is usually connected to tournaments or league situations where there is a referee, tournament director, or league director. If the officiating person determines that a player has behaved in an unsportsman-like way, the penalties could include loss of game and even, at times, loss of match. For example, if you are using a two-piece cue and you unscrew it during the match, that is considered a potential shark move against your opponent, and the officiating person may declare loss of match.
Fouls consist of scratching, missing a call shot (without hitting any cushions), or missing a shot as designated by rules imposed by players.
It's not that easy to foul. In most games, you will most likely miss a shot before you will foul. Missing a shot just means you miss your turn, which isn't a foul. This will be more detrimental when you play with experienced players because you lose control of the table to your opponent and if that player knows his or her stuff, you could lose the game.
There are only a couple of penalties imposed on fouls:
Ball-in-hand
Ball-in-hand behind the head string (mostly in eight ball)
Loss of turn occurs for every foul, but is not necessarily accompanied by a penalty. This is not really considered a penalty; it is more of slap on the wrist.
Ball-in-Hand
To take the “ball in hand” means that if you foul, your opponent can take the cue ball (ball-in-hand) and place it anywhere on the table and pick a shot. This gives your opponent a huge advantage, not only because you've turned the table over to him or her, but also because he or she can basically hit whatever balls are within range. If the player is experienced, this could be the end of the game! Just like a football player wants to keep the ball in play and not lose it to the other team, a pool player needs to keep his or her play in action to keep control of the table.
Ball-in-Hand Behind the Head String
The head string is the imaginary line that runs parallel to the head rail of the table (two diamonds up from the head rail). It is the area of the table where you place the cue ball to break the balls at the start of the game. This penalty allows your opponent to place the cue ball anywhere behind the head string (or in billiards-speak: “in the kitchen”) and pick his or her next shot from that location on the table. This penalty occurs most often in eight ball. In the game called “one pocket,” instead of getting ball-in-hand, one of the balls you previously and successfully pocketed will be returned to play.
Knocking balls off the table is always considered a foul and the penalties vary depending on the game.
Foul with Purpose
Have you ever heard the expression “dirty pool”? Colloquially, it means to do something underhanded. In billiards it means to commit a foul on purpose to throw off your opponent's next move. Sometimes it is necessary to foul to prevent your opponent from winning the game. For example, if it is your turn and you see that your opponent is in a prime situation to win the game if you miss the next shot, you may want to commit an intentional foul to foil your opponent's potential win. This is a common maneuver in playing “safety.” You will use this technique in some games more than others. You'll learn more about that later.
