The term "hype train" is an idiomatic expression that refers to a phenomenon where there is a lot of buzz, excitement and anticipation surrounding something or someone. This could be due to marketing efforts, word-of-mouth promotion, or simply the inherent quality of what's being hyped. The phrase often used in relation to new products, movies, music releases, sports events, political campaigns, etc., where there is a lot of build up and anticipation leading up to its release/event.