Dominoes are small, rectangular blocks that can be stacked on end to form long lines. When a domino is knocked over, it can set off a chain reaction that continues until all of the dominoes are falling. Dominoes are popular as a fun way to make shapes and play games. People also use them to create artworks and to build structures.

Lily Hevesh began playing with dominoes when she was 9 years old. She loved setting up the tiles in straight or curved lines and flicking them to watch them fall, one after the other. Then, as a teenager, she started creating her own amazing domino sets. Now, at 20, Hevesh is a professional domino artist, whose creations have been featured in movies, TV shows, and events—including the album launch for singer Katy Perry. She has a YouTube channel with more than 2 million subscribers, where she shares tips and tricks for creating mind-blowing domino setups.

The rules of domino vary by game, but in most games a tile can only be played if it has a matching side to the previous domino in the line. This side is called the “open” end of the layout, and additional dominoes can be added to the line only by laying them agains an open end or a straddling double (a domino with one side touching another domino). In some games, all four sides of a straddling double are considered open ends.

Each domino has an identity-bearing face with a pattern of dots, or “pips,” that differ from one another. A domino’s other side is blank or identically patterned. When a domino is placed, its pips connect with the pips on adjacent tiles to form a domino chain. The number of pips on the dominoes determines its value in a game.

Players accrue points during game play for certain configurations, moves, or emptying their hand. Typically, the person who has the lowest total number of spots on their remaining dominoes wins. Some games have no winner at all; in these cases, play ends when a player is unable to add any more tiles.

The best-known domino game is draw and match, in which each player draws and then lays down one tile at a time. Each tile must be matched to the previous domino in the chain by its open end. For example, if the first tile laid is a 6-6, the next domino must be a 6-6, 5-6, or 4-4. If the last tile laid has a matching end, then the player is said to have “stitched up” the ends of the chain. In some games, each player calls out the highest domino they have in their hand—for example, “double-six?”—and then takes turns picking and laying tiles until someone plays that domino. Alternatively, each player may pick and lay a different type of domino until an opening double is found.