Entertaiment is an activity that is understood objectively, entails communication between text and audience from an external stimulus, offers pleasure, requires audience participation, occurs in a passive form, has the potential to evolve and is based on the psychological effects of stimuli on the human brain which causes it to release seratonin and other chemicals. It often hits on themes the mind was evolved to deeply react to in order to function in a social world – eg social backstabbing, murders etc.
Entertainment is a broad concept that can be adapted to any scale, from the individual choosing private entertainment from an enormous catalogue of pre-recorded media products, to banquets adapted for two, to performances staged for thousands and broadcast for global audiences.