Defence

Defence (spelled "Defense" in RuneScape Classic; often abbreviated as Def) is one of the primary combat skills. It grants players protection in combat; opponents will land fewer successful blows against a player with a higher Defence level. Additionally, players with higher Defence levels can equip higher quality armour.

Although Defence is often viewed as a "melee skill" because it is commonly trained through melee combat, Defence is a general combat skill that applies to all forms of combat, including Magic and Ranged as well as melee. For this reason, Defence is one of the skills that will raise the combat level of a player regardless of other skill levels, much like Constitution.

Fighting defensively
Defence plays an important role in all forms of combat. The higher a player's Defence level, the more likely an opponent is to miss with an attack, dealing 0 damage. By contrast, equipping powerful armour will merely reduce the amount of damage taken from successful blows. 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 or powerful Summoning familiars.

Defence can be trained in combat using any of the three combat styles: Magic, Melee or Ranged
 * Players fighting in melee combat can receive Defence experience in one of two ways: Fighting in either the Defensive attack style or the Controlled style. The Defensive style gives 4 Defence experience per 10 points of damage dealt (or damage dealt divided by 2.5) and is available with all weapons, including unarmed combat. The Controlled style gives 1.333 Defence experience per 10 points of damage dealt, as well as equal experience to Attack and Strength, but is only available with certain weapons (such as spears and longswords). It is worth noting that the Defensive stance gives an invisible +3 boost to Defence, and the Controlled stance gives an invisible +1 boost to Defence as well as Attack and Strength.
 * Players using Magic can train Defence while casting offensive spells by toggling the "defensive casting" option in the lower left corner of the spells menu. 1 Defence experience (as well as 1.333 Magic experience) will be awarded for every 10 points of damage dealt.
 * Players using Ranged can earn Defence experience by using the Longrange attack style, which splits experience between Ranged and Defence. 2 Ranged and Defence experience will be earned for each 10 damage dealt.

Neglecting Defence
Some players believe that training Defence is unnecessary and instead focus on the offensive skills of their chosen style(s), such as Attack, Strength, Ranged and Magic. These players, commonly known as combat pures, generally possess better offensive capabilities than their combat levels suggest, which can be useful for player killing. Some of these players leave Defence at level 1 and wear iron armour; some raise Defence to level 20 for initiate armour, and some may raise Defence to level 40 for rune armour or 45 for a berserker helm.

While potentially effective in player-vs-player combat, this approach could be dangerous for situations which involve fighting against monsters, such as when completing Slayer assignments.

Defence pure
Rather than ignoring Defence altogether, some players train the skill almost exclusively, resulting in a very high Defence level for their combat level, but limited offensive capabilities. These players are known as defense pures or simply tanks. Some may also train Summoning in order to become Summoning tanks.

Temporary boosts

 * Defence cape - Boosts Defence by 1 level (100/99, must be wearing it, and operate it).
 * Defence potion - Boosts Defence by 3-12 levels (3 + 10% of Defence level, rounded down).
 * Super defence potion - Boosts Defence by 5-19 levels (5 + 15% of Defence level, rounded down).
 * Extreme defence potion - Boosts Defence by 5-26 levels (5 + 22% of Defence level, rounded down).
 * Saradomin brew - Boosts Defence by 25%.
 * Prayer - Thick Skin, Rock Skin, Steel Skin, Chivalry and Piety boost Defence by 5%, 10%, 15%, 20% and 25% respectively.
 * Ancient Curses - Leech Defence and Turmoil boost Defence level by 5%, then up to 10% after time, and 15% + 15% of the opponent's level respectively.
 * Excalibur's special attack boosts Defence by 8 levels.
 * Enhanced excalibur's special attack boosts Defence by 15%, in addition to its healing effect.
 * Cabbage from Draynor Manor boosts Defence by 1 or 2 levels.

Familiars providing Defence boosts

 * Stony shell - The special move of the granite crab boosts Defence by 4 levels.
 * Testudo - The special move of the war tortoise boosts Defence by 8 levels.
 * Titans Cons. - The special move of the elemental Titans boosts Defence By 11%+1

Damage soaking
On 14 December 2010, an update enhanced the defensive values of many pieces of armour with a property known as damage soaking. Any damage above 200 will be absorbed by the armour by the percent indicated in the equipment interface; for example, a hit of 300 melee damage on a player with 20% melee absorption will only deal 280 damage. (20% of the damage greater than 200 was absorbed.)

The absorption values of various pieces of armour are tied to the combat triangle, as opposed to the armour's specific bonuses. For example, Dagon'hai robes, despite giving no melee defence, possess a small bonus to Absorb Melee.