Definition.
Affect is emotion; also how we ‘wear’ our emotions in our facial expressions, body language, and behaviors.
Affect is central to the idea of the complex. In the third volume of his Collected Works Jung notes that strong affects make for powerful complexes. Constellated complexes are, in turn, accompanied by a distinct affective charge. When the emotion is spent, the complex recedes back into the unconscious portion of the psyche.