Set is a game invented by the geneticist Marsha Falco in 1974. The deck consists of 81 cards varying in four features: number (1, 2, or 3); size (large, medium, or small); shading (solid, brightened, or open); and color (red, green, or blue).
Each card is unique. The objective of the game is finding the 4 hidden sets among 12 random cards.
A set consists of 3 cards which fulfill all of these conditions: They all have the same number, or 3 different numbers.
They all have the same size, or 3 different sizes. They all have the same shading, or 3 different shadings. They all have the same color, or 3 different colors.