Lighting is an important element in horror film trailers. Common lighting techniques used include ambient lighting to create realism, profile lighting to show two sides of a character, and backlighting or underlighting to generate suspense through silhouettes or ghostly effects. The document discusses how lighting in horror emphasizes darkness and the unknown to build fear and tension in viewers. It also notes that the film The Conjuring effectively uses dark and limited lighting in its basement scene to leave what may be lurking in shadows up to audience imagination.