Dominoes are small tiles that can be stacked on end in long lines. When one of the dominoes is tipped over, it causes the rest of the line to fall, creating a chain reaction that can build up to some very large and dramatic structures. Dominoes can also be used to create artistic designs such as straight or curved lines, grids that form pictures, and 3D structures such as towers and pyramids.

Dominos have a long history of being used as a game and a learning tool. Children often enjoy laying them out in rows and then toppling them, but they are also used for more intricate projects such as building houses and cities. Stacking dominoes in curved lines, for example, can create intricate designs that have to be seen to believe.

The most common domino size is about two inches long, a little over an inch wide, and three-quarters of an inch thick — small enough to be held comfortably in the hand, but large enough to manipulate easily. The face of each domino is typically marked with an arrangement of dots, called pips, which are similar to the spots on a die. The opposite side of the domino is blank or identically patterned. Normally, each domino has the same value on both ends, but the number of pips on the two exposed ends may be different: a domino with a 2 on one end and 5 on the other is considered to be worth more than a domino with 2 on one end and 6 on the other.

Many games are played with dominoes, and the basic rules are very simple. In most of these, players take turns drawing and placing dominoes on the table in a row. When a player has all of his or her tiles laid out, he or she scores points by arranging them so that the ends touching each other are matched in value (i.e., a 1 on one end touches a 2 on the other, and a 5 on one end touches a 6 on the other). If both sets of ends match, the player scores that number of points.

Dominoes are most commonly made of polymer materials, but they can be made from a variety of natural materials as well. Traditional European-style dominoes are usually made of bone, silver lip ocean pearl oyster shell (mother of pearl), ivory, or a dark hardwood such as ebony, with contrasting black or white pips. These are often heavier and feel more substantial than polymer dominoes, but they can be more expensive as well.

A 20-year-old Michigan native named Lily Hevesh began collecting dominoes when she was nine and soon began displaying her creations online. Now, her YouTube channel, Hevesh5, has more than 2 million subscribers who admire her dazzling domino art. She creates stunning setups that are used in movies, TV shows, and even at events like a Katy Perry album launch. For Hevesh, the joy of dominoing comes from the reaction it generates: “Dominoes aren’t just about action; they’re about what happens next.”