A short rest is a period of downtime, at least 1 hour long, during which a character does nothing more strenuous than eating, drinking, reading, and tending to wounds.
Once per day, a character can heal 1 hit point per character level at the end of a short rest, up to his maximum hit points. Additional short rests do not provide healing but may give other benefits, depending on a character’s class, feats, and special abilities.