Positive Emotions (Pleasant Emotions)
The valence (subjective experience, usually in terms in attractiveness or aversiveness) of emotions that is characterized by pleasure, pleasantness and motivates approach-type behaviours.
Russell, J. A., & Barrett, L. F. (1999). Core affect, prototypical emotional episodes, and other things called emotion: dissecting the elephant. Journal of Personality and Social Psychology, 76(5), 805-819. doi: 10.1037/0022-35220.127.116.115