Film: Coming soon: the big tease

The movie trailer used to be a simple form of advertising created by studios to hype the product. Now they're every bit as popular as the films they're made to promote. So when did the Coming Attraction become the Main Event?

A man. A film. Alone in the Hollywood jungle. Together they have created the biggest event of screen history. You'll laugh, you'll cry, you'll sneak out your Handycam and make a pirate copy - after months of rumour and speculation, news broke last week that the trailer for George Lucas's Star Wars prequel, Episode I: The Phantom Menace, was finally hitting selected screens across the United States. Within minutes, Hollywood was consumed by trailer madness.

Before you could say "Jedi junkie", fuzzy footage was on the Internet. In one LA cinema, three-quarters of the audience for The Siege rose to their feet exactly two minutes and 20 seconds after taking their seats. In another, which had cannily decided to show the trailer both before and after its main feature, stalwarts endured three hours of Brad Pitt's deadly Meet Joe Black, just to catch another glimpse of Lucas's dazzling montage. Less stoic fans left mid-feature to watch the trailer in neighbouring cinemas, before returning for a third helping.

Films have opened big before, and trailers have always been one of the few types of advertising that people go out of their way to see, but when was the last time a trailer provoked standing ovations? When, in the looking- glass world of movie hype, did a Coming Attraction become The Main Event? In the silent era, film previews consisted of nothing more than hand-painted star portraits on glass slides. But in 1916, Famous Players aired an "advance strip of film" to promote their movie Quest for Life, and the trailer was born.

Since then, trailers have become a movie-going institution, their cliches and conventions developing hand in hand with the pictures they publicise. In the Thirties and Forties, many went for the personal introduction - a black-tie, after-dinner speech that generally featured the star or director stepping out from behind a curtain and earnestly explaining their latest feature. Sometimes they'd deliver their lecture in front of a blackboard, running through the main points of the movie like a teacher hired by the studio to coach a particularly slow group of children.

There were more inventive stunts too. With a story ripped from recent headlines, Warner's 1939 film The Roaring Twenties was shot like a newsreel, and featured the screenwriter, Mark Hellinger, banging away on his typewriter (presumably finishing the script). A few years later, the studio sent The Big Sleep's Humphrey Bogart to the Hollywood Public Library in search of "a mystery novel as exciting as The Maltese Falcon". Ed Sullivan introduced 1954's production of Guys and Dolls by flashing audiences the $3m cheque Sam Goldwyn paid for the rights to the play, while the very Capra-esque promo for Frank Capra's cornball classic, It's A Wonderful Life, seemed bent on brainwashing viewers with repetition: "A Wonderful Film", "About Wonderful People", doing "Wonderful Things".

As always, Hitchcock was ahead of the game. In his sly 1960 trailer for Psycho, the portly ghoul wandered around the Bates Motel feigning delicacy ("The bathroom. Oh, they've cleaned all this up now. Big difference. You should have seen the blood. The place was... well, it's too horrible to describe") while giving viewers a tour of the plot which all but revealed the film's ending.

These days, such leisurely and intimate introductions have given way to an anonymous barrage of clips. Raised on MTV and CNN sound-bites, today's audience demands a speed-edited succession of elliptical images rather than laborious spoon-feeding. Tolerance for long trailers has dropped. Once five-minute "deluxe previews", they have shrunk in the last 20 years to as short as 90 seconds - a concentrated rush of stars and stunts that amounts to a subliminal two-minute movie. If TV is the opiate of the masses, then today's trailers are screen crack: a direct hit of adrenaline and emotion.

Still, if presentation is somewhat more sophisticated, the process of cannibalisation, clarification and simplification remains the same. Trailers sell stars ("Academy Award-winners") and new work from known directors ("from the maker of..."). Or, in the case of recent disaster flicks, forget about their B-list cast altogether, and simply showcase the real stars of the movie: the special effects.

Such reductive editing means that trailers are the purest expression of genre. Take the retro promo doing the rounds for Zorro. It opens with a black-and-white shot of a caped figure in silhouette, who grabs his sword and carves a "Z" into the screen. Colour seeps through the scar, along with a collection of horse-jumping, whip-cracking, rose-presenting, Spanish-dancing, swashbuckling cliches.

Elsewhere, the costume trailer panders to the highbrow aspirations of an anxious, middle-brow audience. "From the classic novel by Joseph Conrad comes an epic story of romance and danger", intones the chocolate-coated voice of the narrator over images of Victory, each superlative freighting the project with a spurious cultural gravitas.

Even the worst movies can look good when boiled down to a couple of minutes, so it's no surprise that some trailers outclass the features they're supposed to be selling. Godzilla's carefully paced teasers certainly trumped the dull spectacle that finally hit the screen almost a year later, while the gorgeous psychedelic trailer for Terry Gilliam's Fear and Loathing in Las Vegas suggests the movie that got away.

Whatever the angle, trailers are there to whet the appetite of their target audience. The best generate their own word of mouth. Remember the singing mice from Babe? Or the thumping sound-track to Mission: Impossible? "Expect the impossible," it boomed, and that's exactly what some trailers ask you to do. Often shot before the movie is finished, they regularly include footage that never makes it to the final cut. Occasionally things happen the other way around. In case of Naked Gun 21/2, Paramount commissioned a special spoof teaser of their box office hit, Ghost - which went down so well with audiences that the director, David Zucker, decided to include the footage in the finished film.

The next stage in this evolution seems to be films that resemble nothing so much as extended trailers. Tony Scott's entire output, or the current vampire flick, Blade, for instance, never get beyond the virtuosity of the preview aesthetic.

Such post-modern decadence is reflected by the way today's audiences gorge on trailers outside the cinema. If you think watching the outdated promos on your hired video makes you a bit of an aficionado, then think again. In the States, there's a roaring trade in trailer compilations, while Cable TV shows, such as Trailer Park, are devoted to promos. On any pay-per-view movie channel, you'll see nothing but trailers. "We give people those channels instead of a blank screen," says Loni Musiello, director of Time Warner Cable of New York City. "Believe me, they watch."

In this country, trailers are providing eye-candy for monitors in retail outlets, night-clubs and student unions. Rumour has it that British cinemas, in an inversion of marketing laws, are so keen to screen the Star Wars trailer that they're offering to pay. Star Wars hysteria. Coming to a cinema near you soon; oh, and some of those feature things, too.