In Dungeons & Dragons (D&D) 5th Edition, "Hit Dice" (HD) serve two main purposes: determining a character's hit points (HP) at first level and beyond, and facilitating health recovery during short rests. Each class grants a character a specific type of hit die, such as a d6 for Sorcerers, a d8 for Rogues, and a d10 for Fighters, which indicates the dice rolled to calculate their maximum HP at level one and additional HP gained with each level up [[1†source]][[4†source]].

During character creation, a player rolls their class's hit die and adds their Constitution modifier to the result. This total becomes the character's starting HP. For subsequent levels, players can either roll the hit die again and add their Constitution modifier and the result to their existing HP or take the average result as specified in the class description, ensuring a steady increase in durability as the character advances [[3†source]].

Moreover, Hit Dice play a crucial role during short rests, a period of downtime in-game lasting at least 1 hour. Players can spend one or more of their accumulated Hit Dice, rolling each and adding their Constitution modifier to recover lost HP. The number of Hit Dice a character can spend is capped at their level, and spent Hit Dice are restored upon completing a long rest, up to a maximum of half the character's total number of Hit Dice [[2†source]][[6†source]].

Hit Dice, therefore, are a vital component of D&D 5e's mechanics, influencing both a character's resilience in combat and their ability to heal without relying solely on magical healing resources.