dieroll

A dieroll is the act of rolling a die to produce a random result that determines outcomes in games and simulations. The term is used broadly in tabletop role-playing games and board games, where dice serve as a tangible mechanism for chance and uncertainty. A dieroll can decide success, failure, damage, or other game effects according to the applicable rules.

Common dice include polyhedral varieties such as d4, d6, d8, d10, d12, and d20. Some games use dice pools, where the results of several dice are added or compared against a target. Others rely on single-die mechanics with modifiers, re-rolls on certain results, or special faces that alter the outcome (for example, critical hits or misses). In addition to standard dice, percentile dice (often as 1d10 with a separate tens die) are used to generate 0–99 or 1–100 results.

Probability plays a central role in dierolls. Each die face has a known probability, typically 1 divided by the number of faces. Modifiers raise or lower effective targets, and multi-die rolls produce sums with greater variance. Some systems employ redistribution rules, such as exploding dice, where rolling the maximum value grants an extra die roll.

In digital contexts, dierolls are simulated by random number generators in software, online tools, and chatbot apps. Proper implementation aims to ensure fairness, reproducibility, and verifiability, often by exposing the number of dice, the type of die, the modifiers, and any rerolls or exploding rules.