Affect, in psychology, refers to the underlying experience of feeling, emotion, attachment, or mood. In psychology, "affect" refers to the experience of feeling or emotion. It encompasses a wide range of emotional states and can be positive or negative. Affect is a fundamental aspect of human experience and plays a central role in many psychological theories and studies. It can be understood as a combination of three components: emotion, mood, and affectivity. In psychology, the term "affect" is often used interchangeably with several related terms and concepts, though each term may have slightly different nuances. These terms encompass: emotion, feeling, mood, emotional state, sentiment, affective state, emotional response, affective reactivity, disposition. Researchers and psychologists may employ specific terms based on their focus and the context of their work.

Feelings are subjective self-contained phenomenal experiences. According to the APA Dictionary of Psychology, a feeling is "a self-contained phenomenal experience"; and feelings are "subjective, evaluative, and independent of the sensations, thoughts, or images evoking them". The term feeling is closely related to, but not the same as, emotion. Feeling may for instance refer to the conscious subjective experience of emotions. The study of subjective experiences is called phenomenology. Psychotherapy generally involves a therapist helping a client understand, articulate, and learn to effectively regulate the client's own feelings, and ultimately to take responsibility for the client's experience of the world. Feelings are sometimes held to be characteristic of embodied consciousness.