Domino is a game of skill, strategy and chance. It can be played on the floor or on a tabletop. It can be simple or elaborate, with straight lines, curved lines that form pictures, grids that create patterns, stacked walls and even 3D structures like towers and pyramids. Domino is also a metaphor for personal growth and achievement, demonstrating how one small action can cause others to follow in its wake.

Domino is the most popular name for a type of flat rectangular block of wood, about thumb-sized, with one side bearing from six to eight pips or spots and the other blank or identically patterned (also called an “identity”). 28 such dominoes make up a typical set. The term can also refer to any of several games played with these pieces, mainly blocking and scoring games, where the player places dominoes in lines and angular patterns and score points according to a specific rule.

In his commencement speech at the University of Texas, Admiral William H. McRaven offered his top piece of advice to graduates: “Make your bed in the morning.” He used this example as an analogy for the power of the domino effect, which shows that taking a small, simple action can have a tremendous impact on other areas of your life. “Domino actions are like a ripple in the water,” he said. “Start with a single domino, and let it spread.”

The most common domino sets are double-six (28 tiles) and double-nine (55 tiles). Larger sets exist but are seldom used for gaming purposes; they tend to be used for decorative displays of domino art.

Each domino has a line that divides its identity-bearing face into two squares, or “ends”; each end may be numbered with up to four pips. The total number of pips on either end determines the value of that domino, which is often referred to as its rank or weight. A domino with more pips is generally considered to have greater value than a similar domino with fewer pips.

In a domino game, players take turns attaching a domino from their hand to the ends of the dominoes already in play. Each domino placed must match its partner in order to complete a chain. When a domino chain is completed, points are scored for each time the sum of the numbers on the two end tiles is divisible by five or three, and for each of the two end tiles that match each other. Dominos may also be grouped into suits, such as the suit of threes or the suit of doubles, to make playing them more efficient. In addition, many games have rules for identifying the suits of the pieces. Identifying the suits is usually done by comparing the color or pattern of the dots on a domino with those on the cards in a deck of cards. This can be done by hand or with specialized software. In some instances, more detailed information is needed to correctly identify the domino, such as the number of pips and the arrangement of those pips on each end of the tile.