Abilities (Japanese: 特性 special characteristic) are a game mechanic in the Pokémon series introduced in Generation III. Individual Pokémon may have just one of these special attributes, which generally serve to assist them in battle. Not every ability is beneficial, though; some can actually hinder the user. Abilities are very similar to Pokémon Powers in the Trading Card Game; in fact, some abilities originally appeared as such.
Some Pokémon may have the option of having more than one ability. In this case, the chances of obtaining a Pokémon with a particular ability are equally likely. These Pokémon are known as "dual ability" Pokémon; similarly those with only one are known as "single ability" Pokémon. Some single ability Pokémon may have abilities unique to themselves or their evolutionary lines: a signature ability. However, in the Mystery Dungeon games, dual ability Pokémon literally have two abilities, which are both active.