A buff is a persistent, often temporary positive effect that generally benefits the person or creature on which it is applied. Barkskin, Protection from Evil, and Haste are some examples.
Guild Airships provide some of the longest-lasting buffs in the game via their amenity bars.
Some buffs are in the form of spells from a player character, non player character or other item. Buffs may last a few seconds, several minutes or, in special cases, hours.
Many buffs can be removed by enemy spell casters or area effects. This is often called debuffing.
The most dangerous debuffing enemy may be the beholder, whose anti-magic cone not only robs most buffs, but leaves spell casters powerless for 3 seconds.
Some buffs with spell-like abilities cannot be debuffed. These include songs from Bards and finishing move effects of Monks.
Unique item sets that create a spell-like effect are also immune from debuffing.