Any relatively brief conscious experience characterized by intense mental activity and a high degree of pleasure or displeasure.
Emotion is often intertwined with mood, temperament, personality, disposition, and motivation.
In some theories, cognition is an important aspect of emotion. Those acting primarily on the emotions they are feeling may seem as if they are not thinking, but mental processes are still essential, particularly in the interpretation of events. For example, the realization of our believing that we are in a dangerous situation and the subsequent arousal of our body's nervous system (rapid heartbeat and breathing, sweating, muscle tension) is integral to the experience of our feeling afraid. Other theories, however, claim that emotion is separate from and can precede cognition.

Emotions are complex; they are a state of feeling that results in physical and psychological changes that influence our behavior.
The physiology of emotion is closely linked to arousal of the nervous system, with various states and strengths of arousal relating, apparently, to particular emotions. Emotion is also linked to behavioral tendency. Extroverted people are more likely to be social and express their emotions, while introverted people are more likely to be more socially withdrawn and conceal their emotions.
Emotion is often the driving force behind motivation, positive or negative. According to other theories, emotions are not causal forces but simply syndromes of components, which might include motivation, feeling, behavior, and physiological changes, but not one of these components is the emotion. Nor is the emotion an entity that causes these components.

Emotions involve different components, such as subjective experience, cognitive processes, expressive behavior, psychophysiological changes, and instrumental behavior.
The different components of emotion are categorized somewhat differently, depending on the academic discipline. In psychology and philosophy, emotion typically includes a subjective, conscious experience characterized primarily by psychophysiological expressions, biological reactions, and mental states. A similar multi-componential description of emotion is found in sociology.

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Adapted from Wikipedia, the free encyclopedia. Internet. Accessed on June 14, 2016.