An Advantage is a secondary trait that is neither an Attribute nor an Ability/Skill. The term is typically used as a catchall term for common traits that fall outside the bounds of those two categories of traits, most notably Willpower and Health.
The term is used to group together otherwise disparate traits in most Storyteller System games, including the Revised Storyteller System. While present on nearly every character sheet, the term was almost never used in the rules; Advantage traits were generally presented in their own sections rather than under a grouped heading, and points were never pooled for purchasing Advantages. Many Revised Edition character sheets further separate some of the more important Advantage traits into a section at the bottom of the page which has no heading.
Traits considered Advantages include Willpower, Health, Backgrounds, Virtues (vampiric and imbued), supernatural powers (e.g. Disciplines, Gifts, Spheres etc.), point pools (e.g. blood points, Quintessence), Merits and Flaws, and anything else unusual, including Humanity, Conviction and "power stats" like Arete, True Faith, Glamour, Rage and Gnosis.
In the Storytelling System, Advantages are secondary traits, several of which are derived from other traits. Defense, Health, Initiative Modifier, Size, Speed and Willpower are Advantages in both the original version of the system (introduced in the World of Darkness: Storytelling System Rulebook) and in the revised version of the system (featured in The God-Machine Chronicle and the Chronicles of Darkness: Revised Storytelling System Rulebook). In the original version, Morality, Virtues and Vices are Advantages; in the revised version, Morality is replaced as an Advantage by Integrity, and Virtues and Vices are reclassified from Advantages to Anchors.