Key conventions of movie trailers include showing key moments out of chronological order to avoid revealing the plot, displaying the title at the end, and showing popular actors and directors early to attract audiences. Trailers also use voiceovers, text, and music to convey genre and style without fully explaining the story. The history of trailers began around 1913 with short clips added to play bills and newspaper serializations to promote films and encourage viewership. Trailers have evolved over time along with changes in filmmaking and culture.