A trailer is a wheeled vehicle that can’t move on its own — it needs to be pulled by a car, truck or other larger vehicle. It’s the kind of thing that parents use to tow their children behind them on bicycle rides, and the kind that people hitch to their trucks to haul camping gear or a boat. A trailer also refers to a film preview that theaters show before a movie, though the earliest trailers came at the end of a feature film, trailing it.

Making a great trailer isn’t easy. A good one encapsulates the central conflict of the film and the stakes for the main characters, and ends on a cliffhanger that makes people want to see the full-length movie to find out how it will be resolved. It’s also important to keep the tone of the trailer consistent with the style and genre of the film, and to create a sense of urgency to get people into the theater.

The best trailers also evoke a specific mood, and use music to convey a particular sound and feel. For example, an action film trailer often uses a fast-paced score to evoke a frantic, exciting feel, while a drama or romance might have a more somber, moody musical track. The use of special effects and acoustic instruments can also add to the overall effect.

Most trailers end with a “billing block”, which is a list of the principal cast and crew of the film. This is usually the same cast and crew that appear on the movie’s posters and print publicity materials. Studio production logos are also featured prominently. If a director or producer is especially well-known, they might be highlighted in the billing block as well.

Trailers have also been used as an effective marketing tool in the digital era, and can be found on websites for movies, TV shows and other media. They can be promoted via social media, email or other online channels, and often include a call-to-action button that leads to the official site for the film or television program. A well-made trailer can help generate buzz for a film and increase its audience, boosting sales and ratings.

Trailers can be used to promote a wide variety of businesses, from mobile boutiques and pet grooming to junk removal, plant care and auto dealing. Some entrepreneurs even use cargo trailers as mobile offices, taking their work with them to the beach, woods or anywhere they can pick up Wi-Fi. While these trailers are typically not as elaborate or polished as a fully-fledged movie, they can still be effective in their own way and have the added benefit of being cost-effective. This makes them a popular choice for start-ups and small businesses that don’t have the capital to invest in a commercial-grade movie production. As a result, they are a staple of the independent film industry.