Acid damage

Acid damage, in terms of the Baldur's Gate series, is an elemental type of damage that circumvents any physical resistances.

Gameplay

 * Resistances greater than 100% will heal the affected creatures, rather than harming them.

Protection from acid
Through the use of certain spells, items or abilities, it is possible to reduce the amount of damage, afflicted by acid.

Spells
Spells usually offer only temporary protection from acid, in varying degrees. … incomplete!

Items
Items, as long as equipped, offer a constant protection from acid. By wearing more than one of these, 100% resistance or even more is quite possible. Consumable items only give temporary protection. … incomplete!

Abilities
There are a few abilities that can offer temporary or constant protection from acid. … incomplete!

Damage from acid
Many spells are based on acid, as well as some abilities, and items may deal bonus or even pure acid damage.

Spells
Due to their purpose of healing and supporting, the arsenal of acid-based spells is much smaller for priests than for wizards. … incomplete!

Items
… incomplete!

Abilities
… incomplete!

Creatures, protected from acid
Some creatures have a natural resistance against acid damage, some have special items equipped that protect them. … incomplete!

Creatures, dealing acid damage
There's is a number of creatures that always or by will are able to deal acid damage, either naturally, via spells or through special items in their equipment. … incomplete!