Hit points and damage

Every character (PC, NPC, and monster) has Hit Points (HP). When a character gets hurt, knocked around, roughed up, or otherwise takes abuse, they lose HP. This is called "taking damage;" when you do it to someone else, it's called "dealing damage." When someone is reduced to 0 HP, they are out of the action and quite possibly dead or dying.

HP are a game element: they don't represent any one particular thing in the fiction. They're a combination of fighting spirit, determination, pluck, luck, and skill; the ability to turn what should be a lethal blow into a graze. HP definitely are not a measure of how injured or uninjured a character is.

Mechanically, HP serve as plot armor and as a pacing mechanism. A PC with 20 HP can be confident that they'll survive the first exchange in a fight. But once a PC has only 5 or 6 HP remaining, any blow from any foe could take them out—and that makes everything more tense and dangerous.

PCs generally have more HP than NPCs or monsters. That's because they're the protagonists; we're telling their story, so they

Taking damage means losing HP, potentially being taken out of the action. A character takes damage when...

• … a player-facing move specifically says that they do;
• … you hurt them (they take damage along with the fictional hurt);
• … you use up their resources, and HP are the resource you use up; or
• … you make any GM move that involves them getting hit, knocked around, roughed up, suffering pain, etc.

If you make a GM move and that move could theoretically kill, disable, or knock out a normal person, then deal damage as well. Dealing damage should almost never be your move, but it will often be part of your move.