Entertaiment is amusement or distraction usually involving a performance. A clown at a birthday party, a Broadway show, a stadium rock concert, your friends fighting over the last potato chip–all are forms of entertainment. The word comes from the Old French entretenir, which meant “hold together” or “support,” and later came to mean amuse or distract. Theatrical entertainment is often called a show, visual entertainment as stuff you like to look at, and audio entertainment as mostly music.
Entertainment is a powerful tool, and can hit on themes that the brain was evolutionarily shaped to react deeply to, such as social backstabbing or murders. This can trigger the brain to realease seratonin and dopamine, making us feel good.