Even for the most casual player, it's important to know the penalties of fouls, because you may find yourself with loss of game in certain games if you foul three consecutive times. So, get to know your rules and make sure both you and your opponent or friend have an understanding ahead of time.
A foul consists of:
Breaking a general billiards rule.
Breaking a rule as set by the players at the beginning of any game.
Breaking a specific rule of a game.
Pushing the cue ball versus striking the cue ball in certain instances.
Touching the cue ball (or object balls in some instances) with anything other than the cue tip (except in the case of “ball-in-hand” which you will read about in this chapter).
Sending a ball off the table.
Scratching (knocking the cue ball into a pocket).
Jumping can be considered a foul depending on the designated rules of that particular game.
Outside interference: If someone accidentally bumps into the table causing the balls to move, the balls should be replaced as close as possible to their original positions on the table.
Some players will mark their aiming point on the table by placing a piece of chalk on the rail. If you do not remove it from that spot before you shoot, you will commit a foul. Be aware that marking the table for the purpose of aiming is generally illegal.
For a seasoned pool player, committing a foul has bigger stakes because it can mean losing the game altogether, not because they are eliminated from the game, but because at a high level of play, they can bet that their opponent will take control of the table and win the game.
Depending on the game you're playing, you can suffer some pretty serious consequences by fouling. One of the gravest is having to turn over ball-in-hand to your opponent. Your opponent then gets to take the cue ball in hand and place it anywhere on the table he or she wants. If you're opponent is a skilled player, it could mean that you may not return to the table again and subsequently, lose the game.
As you can see, the reason this would be detrimental for more-experienced players is because they usually have more success at pocketing several consecutive balls (otherwise known as a good “run” on the table) and a foul could mean the opponent's win. Less-experienced players don't run such a big risk, but ball-in-hand will still bring your opponent ever closer to the win.
Cue-Ball-in-Hand Behind the Head String
In some games, a foul will result in the cue-ball-in-hand behind the head string. In this case your opponent can place the cue ball on the table anywhere within the head string (otherwise referred to as “the kitchen”). This rule applies in some games, such as 14.1 continuous and sometimes in eight ball, depending on which rules you are using. Other games will have different rules regarding fouls and ball-in-hand. You'll read more about those rules in the specific game chapters.
This isn't always as smooth sailing as it may sound. When a player gets cue-ball-in-hand behind the head string, he or she cannot strike any ball on the table. The player can strike an object ball either whose base (the part of the ball making contact with the cloth) is within the head string, or he or she can bank off a cushion outside the head string to strike an object ball inside of the head string. The cue ball can be adjusted by hand, but it cannot be touched again after it has been struck with the cue.
In both ball-in-hand situations, you cannot place the cue ball in position with the cue tip. That is considered a stroke and results in a foul. The best way to place a ball-in-hand cue ball is to position it with your hand. If you like to live dangerously, you can adjust it with the shaft of your cue stick, but make sure you don't touch it with the tip.