OST stands for Original Soundtrack, which refers to the songs or tracks specifically composed for a movie, television show, video game, or any other type of multimedia project. They may be instrumental, vocal, or both, and often contain themes and melodies meant to evoke the feeling of the project they are accompanying. OSTs are often used to create an emotional response in the viewer or listener and can be any genre of music, including rock, pop, hip-hop, and classical. They are particularly popular in movie trailers, as they can help create an exciting and suspenseful atmosphere.