Affect, emotion, and mood compared
In psychology these three terms describe related but distinct phenomena. Affect is the broadest and most basic: the immediate, often brief experience of feeling, frequently described along dimensions of valence (pleasant to unpleasant) and arousal (calm to activated). Emotion is more specific and usually has an identifiable object or cause, such as fear of a particular threat or joy at a particular event, and tends to be short-lived and intense. Mood is a more diffuse, longer-lasting state that often lacks a clear trigger, like feeling generally irritable or cheerful for hours or days.
Why the distinction is useful
Separating these helps clarify everyday language and clinical description. An emotion typically arises in response to something and fades when the situation changes, while a mood colours how a person interprets many situations over time without pointing to one cause. Affect, in this framing, is the raw underlying tone that both emotions and moods draw on. The boundaries are not rigid and researchers define them in slightly different ways, but the duration, intensity, and presence or absence of an object are the usual axes of comparison.