When you roll a 1, something bad happens; when you roll a 20 something good happens. It is a simple roll in many systems that can be the curse or bane of players and GMs. Today we're going to be discussing it in D&D 5E, however this rule applies lots of places. Lets get some terminology out of the way first. An attack roll is made when a creature attempts to hit a target using a weapon (which could a natural, like a fist or claw) to hit a target. A saving throw is a a creature trying to resist or avoid an effect of something like a spell or a trap. A skill check is used when a creatures applies its knowledge to answer a question or its skill to perform a task. For our purposes, this creature will be a player character. For attack rolls, a 20 deals double damage dice, and a 1 misses in 5E RAW. These two effects nearly cancel each other out over the long haul, although not perfectly (math left as an exercise for the reader). Every PC on every attack has the same change...
Chronicles of an Elder GM Running, Hacking, and Sharing Advice on TTRPGs