Tanks are usually heard of in the context of a group, where the tank will be the character with the most protective armor and defensive skills. The tank typically takes the bulk of the damage in combat, protecting the mages and spellcasters while they prepare spells.
The tanking skill is used by warriors to protect their group. To enable the skill, use the 'tank' command while grouped.
A warrior with the tanking skill will automatically attempt to rescue members of the party and protect them from melee combat. Multiple tanks can be used simultaneously to more effectively protect group members.