A 20-sided die, often referred to as a d20, is a polyhedral die commonly used in tabletop role-playing games like Dungeons & Dragons. It has twenty triangular faces, each numbered from 1 to 20. Players roll the die to determine the outcome of various actions, such as attacks or skill checks, making it a crucial element in gameplay. The shape of the d20 allows for a wide range of possible outcomes, providing a more varied experience compared to traditional six-sided dice. Its unique design and use in gaming have made it a popular choice among players and collectors alike.