A D20 is a twenty-sided die commonly used in tabletop role-playing games, such as Dungeons & Dragons. It is shaped like a polyhedron, specifically an icosahedron, and features numbers ranging from 1 to 20 on its faces. Players roll the D20 to determine the outcomes of various actions, such as attacks or skill checks, making it a central element in gameplay. The D20 is part of a larger set of polyhedral dice, which includes other shapes like the D4, D6, D8, D10, and D12. Each type of die serves different purposes in games, but the D20 is particularly significant due to its role in the d20 System, a game mechanic that emphasizes chance and strategy.