A healer is a type of character class in video gaming. When a game includes a health game mechanic and multiple classes, often one of the classes will be designed around the restoration of allies' health, known as healing, in order to delay or prevent their defeat. Such a class can be referred to as a healer. In addition to healing, healer classes are sometimes associated with buffs to assist allies in other ways, and nukes to contribute to the offense when healing is unnecessary.
A description of Healers from the Nethack guidebook is as follows: Healers are wise in medicine and apothecary. They know the herbs and simples that can restore vitality, ease pain, anesthetize, and neutralize poisons; and with their instruments, they can divine a being's state of health or sickness. Their medical practice earns them quite reasonable amounts of money, with which they enter the dungeon.
When both healer and tank classes exist, a common grouping strategy is for the healer to focus healing on an allied tank, while the tank prevents other allies, including the healer, from losing health.
Healers are often represented as a fantasy spell-caster (such as a cleric, druid or shaman), a realistic combat specialist (such as a medic or paladin), a science-fiction technician (such as a repairman or engineer), or the like.
A healer is generally tasked with restoring health, removing poison-like effects, and reviving fallen party members. Different games may include different mechanics, such as the ability to deal damage or to enhance the attributes of their allies.
If the tank's job is to take damage, the healer's job is to heal it. In small groups, they may also be tasked to heal the group as well, but in large scale group-play there are typically specific healers assigned to party-wide damage (typically taken indirectly, via lesser minions, spells or environment/habitat of the boss).
See also 
- Tank (gaming) is another common archetype focused on drawing enemy damage.
- Spell-caster (gaming) is another common archetype focused on dealing damage, while being relatively weak.
- DPS is another common archetype also focused on dealing damage.
- WoW: The official magazine Spring 2010 (Volume 1, Issue 2). Kill and Cure Pg141- Luis Villazon.
- http://www.nethack.org/v343/Guidebook.html#_TOCentry_2 Nethack Guidebook, entry 2 with character classes.