Resting

Resting allows characters to recover hit points, spell slots, and other resources. There are two types of rests:

Short rest

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.
A character can spend 1 or more Hit Dice at the end of a short rest to regain hit points. The player rolls the die and adds the character's Constitution modifier to it. The character regains hit points equal to the total.

A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps or performs light activity (reading, talking, eating, or standing watch) for no more than 2 hours.
At the end of a long rest, a character regains all lost hit points. The character also regains spent Hit Dice, up to a number of dice equal to half of the character's total number of them (minimum of 1 die).
A character can't benefit from more than one long rest in a 24-hour period, and a long rest is interrupted if the character performs more than 1 hour of strenuous activity, such as fighting, casting spells, or similar adventuring activities.