Trailers are an important marketing tool for films to generate interest and box office revenue. Trailers must convey a sense of the film's narrative, genre, and unique selling point, as well as the release date, in order to appeal to the target audience. Trailers capture viewers' imaginations to influence them to purchase tickets. They are released in advance of a film through various media channels, from cinemas to television to online, in order to build hype in the weeks or months leading up to the release. Analyzing a film's entire marketing package, including elements emphasized across different advertisements, can provide clues to the genre being promoted.