What's Buff mean?

[Ballstone]

I was reading a Sorceress CL/FO build and one of the strategy suggestions he had was-
Bind your offensive spells to your left click and Static/TP/Buff to your right click.

I looked in all the stickies and faqs for Buff. Nothing. Typo?

[JME]

A buff, or prebuff is something you do before going into battle and not a skill typically used in battle. A cast-and-forget skill, so to speak.

Cold Armor and Energy Shield on a sorc for example.
Holy shield on a paladin
BC, BO, and Shout on a barb (or many characters using a CTA with BC and BO)
etc.

Also, when a lot of people refer to pre-buffing, they are putting on specific gear which helps them attain a higher level of the skill they are buffing. Then they take that item off and use their appropriate gear for actual play. For instance, many barbs use warcry spears on switch or keep a +5 BO helm in the stash for buffing. A CTA and spirit on switch is also common for many builds. A special wand for summon necro minions can be useful, etc.

[Ballstone]

I tried pre-buffing and discovered the ONE way that it doesn't work.
I activated a +3 to Death Sentry on switch. Then switched back to primary and all of the traps disappeared. I figured out what happened. I had no real points in DS.

[JME]

I tried pre-buffing and discovered the ONE way that it doesn't work.
I activated a +3 to Death Sentry on switch. Then switched back to primary and all of the traps disappeared. I figured out what happened. I had no real points in DS.

Other "summons" are treated in the same way (traps are treated as summons). If you get a valkyrie, revive, golem or some other type of summon from an item (with no base points) and remove that item, the summon will disappear.

[Darkflight]

Skills that are buffs are spells that you activate to boost yourself or your teammates/merc/summons in some way. They then last for a certain duraton before they expire and you have to cast them again.

The skills you cast on enemies to give them disadvanteges are called debuffs.

List of buffs/debuffs:

Amazon: Slow Missiles, Inner Sight.
Assasin: Burst of Speed, Fade, Venom, Blade Shield, Cloak of Shadows.
Necromancer: All curses are debuffs, Bone Armor.
Barbarian: Howl, Taunt, Battle Cry, Shout, Battle Orders, Battle Command.
Sorceress: Enchant, Frozen Armor, Shiver Armor, Chilling Armor, Energy Sheild, Thunder Storm.
Paladin: Holy Shield
Druid: Cyclone Armor, Hurricane, Werewolf, Werebear.
Monster Buffs: All the curses monsters use are debuffs, I can't recall anything else.

The skills that stuns when you cast them, War Cry, Shockwave and Mind Blast can also be considered debuffs because of the stunning.

The skills that convert monsters to your side, Mind Blast and Conversion, can be considered debuffs.

Things that are similar, but are not buffs/debuffs:

All skils in the Paladins Offensive Auras and Defensive Auras skill trees, Druid spirits aura (Oak Sage, Heart of Wolverin, Spirit of Barbs), all skills that provide passive bonuses.

[JME]

Things that are similar, but are not buffs/debuffs:

All skils in the Paladins Offensive Auras and Defensive Auras skill trees, Druid spirits aura (Oak Sage, Heart of Wolverin, Spirit of Barbs), all skills that provide passive bonuses.

Considering all of those spirits provide bonsuses and stay active even after switching, I would definitely consider them buffs. In fact I prebuff my summons (oak sage, valkyrie, etc) all the time with a CTA and spirit on switch.

Something doesn't have to have a limited duration to be a buff, it is a function of what it is doing, not how long it will last.