Defence (often abbreviated as Def) is one of the primary combat skills that grants players protection in all forms of combat. Defence is one of the skills that will raise the combat level of a player regardless of other levels.
The higher the Defence level, the fewer successful blows an opponent will land against a player, this applies to all combat styles used against the player. Defence is thus a vital skill for enduring attacks for long periods of time, and can be extremely helpful against opponents with high Attack, Ranged or Magic.
A player's Defence level also determine which equipment they are able to wear, as most pieces of equipment have a Defence level requirement.
Almost every piece of combat equipment requires a certain Defence level to wear.