Buff

A buff is a positive change within the game and can refer to several aspects of the game.

Game mechanics
A buff is a change to a gameplay mechanic that is either perceived as positive or wanted. For example: If a spell or skill gets updated to damage or heal for more, cost less to cast, or has a shorter recharge, it has been buffed. In this way a buff is the opposite of a nerf.

Character status
Positive effects that improves traits like attributes, health, energy or speed, or provides some other beneficial effect, such as health regeneration or the ability to block attacks. Usually caused by but not limited to:
 * All title effects
 * All chants
 * All enchantments
 * All weapon spells
 * All echoes
 * All stances
 * Some ward spells
 * Some well spells
 * Some consumables
 * Some rituals
 * Some "basic" skills

Most buffs are temporary, however there are also buffs which persist until a player zones, and title effects persist between zones.

Synonym
Because enchantments are the most common type of buffs in Guild Wars, buff is also used within the context of the game as a synonym for enchantment. For example when a player is asking his or her party members for a buff.