The Lantern Hall
Painting: an ancient lexicon open on a carved lectern in a dark chapel of books, glowing runes and symbols lifting off its pages like fireflies.
TermTabletop term1974

Armor Class

A rating of how hard a target is to hit, combining armor, shield and agility into one number. In early D&D lower was better (plate and shield was AC 2), which made attack math notoriously confusing; third edition (2000) flipped it so that higher is better.

A rating of how hard a target is to hit, combining armor, shield and agility into one number. In early D&D lower was better (plate and shield was AC 2), which made attack math notoriously confusing; third edition (2000) flipped it so that higher is better.

Origin

Credited to Dave Arneson; the idea may have been inspired by the naval wargame Don't Give Up the Ship!, though no attribute of that name appears in its published rules. It entered print with Dungeons & Dragons in 1974.

Quick answers

What does "Armor Class" mean?
A rating of how hard a target is to hit, combining armor, shield and agility into one number. In early D&D lower was better (plate and shield was AC 2), which made attack math notoriously confusing; third edition (2000) flipped it so that higher is better.
Where does the term "Armor Class" come from?
Credited to Dave Arneson; the idea may have been inspired by the naval wargame Don't Give Up the Ship!, though no attribute of that name appears in its published rules. It entered print with Dungeons & Dragons in 1974.

Nearby in the archive

THAC0

Tabletop term

The number a character needed to roll on a d20 to hit a target of Armor Class 0; subtract the target's AC to find the roll needed against anything else. It compressed pages of attack tables into one value, but its double negatives became a byword for clunky rules. It was retired when third edition introduced ascending AC in 2000.

Hit points

Tabletop term1974

A number measuring how much damage a character or creature can take before it is defeated. Attacks subtract hit points and rest or healing restores them, turning the drama of a fight into a steadily falling total. Nearly every Western Computer RPGs (CRPG) and Japanese RPGs (JRPG) inherited the idea, usually as a shrinking health bar.

Dave Arneson

Game designer1947–2009

The Minnesota wargamer whose Blackmoor campaign of 1971 put single heroes, dungeons and hit points on the table, and who co-created Dungeons & Dragons with Gary Gygax.

Painting: three small plain tan rulebooks in a wood-grain cardboard box beside strange new polyhedral dice, pencils and a graph-paper dungeon map.

Dungeons & Dragons

Tabletop RPG1974

Three little booklets in a woodgrain box, hand-assembled in Lake Geneva in January 1974: the first published roleplaying game, and the template for every tabletop and computer RPG since.

Dungeons & Dragons 3rd Edition

Tabletop RPG2000–2008

Wizards of the Coast's rebuild of D&D around one rule — roll a d20, add modifiers, beat a number — released alongside an open license that let anyone publish for it.

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