I've been noticing over the last year a significant increase in the use of the term "fan service" in not only Bald Move casts, but most TV podcasts. Most recently, @Jim and @A_Ron_Hubbard have been using it in several of the Stranger Things casts. In the 2.01 cast, they said that the arcade scene, with Dragon's Lair and Dig Dug video games, was fan service. I don't understand how this is fan service. My question is this: What's the difference between world building, homage, and fan service? What kinds of things qualify as fan service?