Heal over time

Heal over time (generally abbreviated as HoT) refers to a type of healing ability. A HoT does not immediately heal a target; a HoT instead heals the target for a certain amount over regular intervals. In World of Warcraft, the healing is typically applied every X seconds (X varies between different HoTs). A HoT may be applied using a variety of methods - from a spell, a bandage (see First Aid), eating food, a potion or some other form. Most HoTs are target specific, though there are also Area of Effect (AoE) HoT's such as the Druid spell Tranquility.

A HoT is in principle a Buff, but usually with a much shorter duration than "normal" buffs. HoTs can usually be removed or dispelled, just like Buffs.

The Druid is the most well-known class for using HoT spells, probably followed by the Priest. Shaman and Paladins have spells which heal over time but the methods are different from the simple buffs of priests and druids. Warlocks and Hunters also have HoTs, although they are not often seen since they are limited to themselves or their pets.

Examples

 * Priest: Renew, Penance (Discipline specialization, channeled), Holy Word: Sanctuary (with talents)
 * Druids: Rejuvenation, Regrowth, Tranquility (channeled, AoE), Lifebloom, and Wild Growth
 * Shaman: Healing Stream Totem, Earthliving Weapon, and Riptide (with talents)
 * Paladin: Eternal Flame
 * Warlock: Drain Life (self only, channeled), Health Funnel (channeled, pet only)
 * Hunter: Mend Pet (pet only)

Limitations

 * It is not possible to stack the same HoT from a single healer, but the same HoT from different healers can stack on one target. The exception is Lifebloom, which can be stacked 3 times by the same druid.
 * Bandage HoTs are interrupted when the "caster" or the target take any form of damage.

Tips

 * Don't waste mana by putting a HoT on someone who is *not* going to take damage.
 * Exception to the above rule: Feel free to give out HoTs to Warlocks. They "damage" (Life Tap) themselves frequently to make mana. Apply an occasional HoT and you will quickly become their new best friend! And you will be helping, in a very simple way, to maximize the DPS of your party or raid. (Especially if your Warlock buddy is Demonology-specced, as they have the least self-healing of the warlock specs)
 * Each tick of a HoT can cause aggro, but it's spread out over time allowing the tank to build up aggro to counteract it. The difference between HoT and direct heal aggro is consistently gaining small amounts of hate versus gaining no hate for a period of time followed by a sudden large spike in hate.  As with all healing, however, the threat generated is split among all targets in combat, and overhealing generates zero threat.
 * Some people like to put a HoT on their tank as soon as they start taking damage, though this may not be advisable if the tank does not generate aggro well. Make sure your tank can at least grab as much aggro per tick as your HoT.  This is usually not a worry since a good tank can generate far more aggro per tick than a HoT.
 * Whether a HoT generates aggro depends on whether the healer is in combat with the mob. If the healer isn't in combat with the mob, no threat is generated. In a 5 man instance, it is usually safe to HoT the tank before the pull; the healer won't be put in combat immediately and therefore won't get any aggro. In raid encounters, every raid member enters combat once the boss is pulled. It is therefore only advisable to HoT a tank who is pulling a raid boss if the tank has Hunters or Rogues helping him out with Misdirection/Tricks of the Trade or if the tank can securely establish threat on the pull with a high-threat ranged ability such as Heroic Throw or Avenger's Shield.