Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria. In psychology, the pleasure principle describes pleasure as a positive feedback mechanism, motivating the organism to recreate in the future the situation which it has just found pleasurable. According to this theory, organisms are similarly motivated to avoid situations that have caused pain in the past. The experience of pleasure is subjective and different individuals will experience different kinds and amounts of pleasure in the same situation. Many pleasurable experiences are associated with satisfying basic biological drives, such as eating, exercise or sex. Other pleasurable experiences are associated with social experiences and social drives, such as the experiences of accomplishment, recognition, and service. The appreciation of cultural artifacts and activities such as art, music, and literature is often pleasurable.