A trailer is first and foremost a piece of advertising, designed to sell the cast and concept of a film to audiences. Unlike other products, a new movie really only gets one shot at success. It either opens or it bombs. As Intralink president Anthony Goldschmidt puts it, new movies don't sit on the shelf like Tidy Bowl or toothpaste waiting for customers to get around to trying the product. So, unlike other forms of advertising, a movie preview must stir up immediate interest in the film.

"Here, there are no rules because we're really not selling you anything," Goldschmidt says. "If we can make you laugh or cry or scare the hell out of you, then we've done a really good job. That movie is working. And if the campaign alludes to that, then the campaign is doing the right thing, because its obligation is first and foremost to get you to part with eight dollars. That's the reality of it. Secondarily, it is to get you to part with eight dollars because you have an expectation of something intangible."

Bottom line: Is it compelling? More specifically, does the preview compel the right audiences to shell out eight dollars to see a movie within the first few days of its release? If audiences don't want to see the movie, then the trailer — no matter how innovative, artistic, or cool it may be — hasn't done its job.

Studios use a very matter-of-fact standard for gauging trailer effectiveness: "Butts in the seats," they call it. If audiences don't turn out in massive numbers on opening weekend, the movie may get pegged as a failure. And if the movie is a failure, the trailers are held personally accountable.

"There's a big blame factor in the business," Goldschmidt says. "If the movie opens, the studio calls the filmmakers, the producers, and they say to them, 'You guys are the greatest. Look at these numbers.' They crack open the champagne, and they try to make another deal with them. And no one calls us because what we did had nothing to do with the opening of the movie. It was the movie: The movie's great!

"But if the movie goes into the tank, the filmmakers call the studios and say, 'Well, your advertising sucks. We told you it sucked all along, and you wouldn't listen. You've sabotaged the movie, you bastards!' And we get blamed. So it's a no win, no win."

Theatergoers are always promising to put off seeing a movie until it's released on video, especially in the case of your standard genre picture where the interest just isn't strong enough to justify the full ticket price. Consider a new romantic comedy where the stars change but the story remains largely the same. The previews may convince audiences that they eventually want to see the movie without being compelling enough to inspire any sort of immediacy.

Unfortunately, there's no way to measure the public's intention of seeing a movie, and that kind of interest has little positive bearing on a movie's first weekend, when the distributors take their biggest cut of the box office.

What really matters is how excited a trailer makes audiences before any other influences have the chance to affect their decision. Word of mouth ultimately has a far greater impact on whether or not someone might see a movie, but it still takes a catchy trailer to inspire attendance among those reliable friends, classmates, or coworkers who might eventually end up recommending the film.

"If the marketing materials are provocative independent of the film, if they arouse curiosity and interest, shouldn't that film at least do opening business?" asks Goldschmidt. "Theoretically no one has seen the film, so if nothing else, shouldn't the first day's box office be okay? You will not outbuy word of mouth. The word of mouth will travel faster than you can spend your money, so if it's just a piece of shit, the word's going to go out like wildfire. But before anyone has seen it, how do they know?"

Previews often combine with a number of other important factors including the critical response, popularity, and buzz about a film before convincing audiences of a movie's "must see" status. Trailers don't always receive the credit they deserve when a movie like There's Something About Mary takes weeks before climbing to first place at the box office. But audiences are frequently wary to go to a movie they haven't heard of, and previews expose them to the sample scenes and jokes they need to consider a recommendation.

As long as the movie business has been a business, distributors and theaters alike have needed ways to keep audiences coming back. To maintain interest, exhibitors began showing slides or even the first reel from upcoming movies to whet audience appetites. Over the years, advance promotional efforts have evolved to accommodate more sophisticated advertising tactics before reaching the preview form we know today, where expert editors strive to condense films into 2 1/2-minute mini-movies without diluting the emotion. A daunting task, indeed, but there are men who can do it, editors with a gift for cutting trailers, artists with an eye for the moments that capture the essence and excitement of a movie.

"In the early days, every director and his editor wanted a chance to cut a trailer," explains Andrew Kuehn, who has been working in the trailer business since 1960. "They'd all take a crack at it, and then they'd realize it's a whole different style of cutting. It's completely different than cutting a feature film, and they all abandoned that. Today no director and his editor cuts trailers. It's all done by the trailer houses. But there was a big struggle for years where that went on until all those editors threw up their hands and said, 'I don't know how you do it!'"

Trailers aren't constructed the same way that movies are, so it makes sense that the two separate forms should require different editing styles. In a movie, the editing must convey a coherent narrative; trailers need only suggest the story. Movies show high points and key scenes; trailers do better to hint at them. Movies ought to offer some sense of satisfaction; trailers should tease us and leave us craving more.