Self-awareness is the ability to perceive one's own existence, including one's own traits, feelings and behaviours. In an epistemological sense, self-awareness is a personal understanding of the very core of one's own identity. It is the basis for many other human traits, such as accountability and consciousness, and as such is often the subject of debate among philosophers. Self-awareness can be perceived as a trait that people possess to varying degrees beyond the most basic sentience that defines human awareness. This trait is one that is normally taken for granted, resulting in a general ignorance of one's self that manifests as odd contradictory behavior. This ignorance of one's own self is viewed in existentialism and Zen buddhism as the source of much human suffering, as noted by the famous saying from Zen buddhism "we are each the source of our own suffering."
In theater, self-awareness refers to an actor who has broken character, perhaps by breaking the fourth wall. The actor acknowledges to the audience in some fashion that he is playing a character. Unintentional self-awareness is extremely unprofessional, though it often acts as a comedic device when done intentionally. Self-awareness can prevent the audience's suspension of disbelief.
See also: Sentience
