Dominoes are rectangular blocks of clay or other materials, normally twice as long as they are wide. They feature a line in the middle to divide them visually into two square ends, each of which has a number of dots or pips that can range from six pips down to blank (or none). Each domino has an open end on its opposite side that may be matched with another, either in the same hand or in the same line of play. When players match and play a domino, the opening end of that tile matches one of the pips on the next one in the line of play, and the line continues to grow. Dominoes are played in many different ways and there are a great variety of games with a domino set. Some games are a race to see who can get their entire line of play down first. Others are positional, and players place their tiles edge to edge with one another so that they form a particular total or pattern. Still other games involve matching a specific value to each domino in the line of play, such as counting the number of pips on the winning player’s tiles that were left in his or her hand at the end of a hand or the game.

Most domino games are played between two or more players. A hand of seven tiles is drawn by each player. The player who draws the highest double goes first, but players who cannot make a play draw additional tiles to their hand until they have a total of seven. The remaining tiles remain in the unused dominoes, called the stock. When a player is unable to continue a turn, he or she must bye some of the unused dominoes from the stock.

Some domino games involve the use of a specialized type of domino, called a spinner. These have an open end that can be matched with a single, double or triple, and they allow for more complex and interesting patterns to be built. Other special rules apply when playing with spinners.

There are a variety of rules that govern how to score domino games, and the rules differ from country to country. One way to count the pips of a winning tile is to add one or both ends of a double; this method is sometimes used in combination with the standard scoring system, which counts only one end of a double.

A domino effect is a term that describes the continuing sequence of events stemming from just one small trigger, such as a political situation or an accident. The idiom was popularized in the United States during the Cold War, when President Dwight Eisenhower cited the example of a falling domino in response to a reporter’s question about America’s decision to offer military aid to South Vietnam. The phrase is also used in other contexts to emphasize the importance of a single action, or even just a nudge, to a larger chain reaction.