Runes are the armor upgrades of Guild Wars. Each piece of crafted armor can hold a single rune, for a total of five runes per character. These runes must be either general runes, usable by all characters, or specific to your primary class - runes cannot upgrade armor for a different class. In addition, the benefits of multiple runes of the same type do not stack, although their HP penalties do (The basis of the "55" build). At the moment there are relatively few runes available for each class, however armor can be further customized with "Insignias" which work in a manner similar to runes.

Depending on a person's style of play, any rune can benefit a build.
Major runes were changed sometime between the Factions and Nightfall campaign releases. Instead of having an HP penalty of 50, they now only reduce a character's HP by 35 points.

List of Insignias A comprehensive list of armor Insignias and their effects.

Rune Effects List A short list of every rune and its effect when equipped.