Attribute

Attributes
Every profession has 4 or 5 attributes, one of them being the primary attribute of the profession. The primary attribute of a profession is only available if the respective profession is also the character's primary profession. For example: an Elementalist/Mesmer has Energy Storage and all other Elementalist and Mesmer Attributes except Fast Casting, while a Mesmer/Elementalist has Fast Casting and all other Mesmer and Elementalist Attributes except Energy Storage.

Rank
Attribute point cost for each rank.

Ranks are the measure of a character's development of a given attribute. Their values indicate how powerful a certain attribute's skills are. Additionally, ranks in weapon mastery attributes (including Beast Mastery) will increase the damage dealt by using the respective weapon type. See Damage Rating progression for details on how weapon mastery attribute ranks affect damage.

Attribute Points (AP) are used to increase an attribute's rank.

The maximum unmodified rank an attribute can be raised to is 12, but the final rank can be modified in various ways:
 * Using a Rune of a certain attribute, which give a character a rank bonus of up to +3. Note that positive Rune effects of the same type do not stack, so having a Rune of Minor Fire Magic and a Rune of Superior Fire Magic equipped at the same time still gives +3 instead of +4, because only the highest positive effect counts.
 * Wearing various Headgears, which can give a +1 bonus to one attribute.
 * Using a non-wand weapon or a Focus Item that has a chance to invoke a +1 bonus to an Attribute when the player uses a skill. This ability has a variable chance of success (10-20%). Wands do not have the +1 ability, while shields only provide +1 for non-weapon attributes, so no profession has a chance of a total +2 rank bonus with this method.
 * Blessings of Gods can temporarily boost the rank by 1. Note this is only available in PvE, not PvP.
 * Necromancers and Elementalists can boost their rank in certain attributes through skills. The Necromancer spell Awaken the Blood provides +2 Blood Magic and +2 Curses for a certain time span. Elementalists have the Glyph of Elemental Power, which boosts all elemental attributes (Air Magic, Earth Magic, Fire Magic, Water Magic) by +2 for the next five spells.
 * Lunar Blessing boosts every attribute by 1. Note this is only available in PvE, not PvP.

The maximum rank a character can achieve in a single attribute is 12 + 3 + 1 + 1 + 1 + 2 + 1 = 21. Or to break it down:

Many players prefer to specialize in 2 or 3 attributes to make most effective use of limited skill slots and AP. For example, a monk dedicated to healing might decide to have 12 rank in both Healing Prayers and Divine Favor. This costs nearly all the character's AP, but allows for maximum effectiveness of skills linked to those attributes. However, because of the quickly diminishing returns of higher ranks, it is a viable strategy to diversify into 4 or more attributes if a Build requires doing so.