Usually just one to three minutes long, the best book trailers swiftly inform potential readers of what to expect. But unlike most movie previews, these trailers are often interpretive, rather than plot-focused; they spring from the imagination of their creators, as well as from the books they represent. Search YouTube and you’ll find thousands of examples.

With a little help from Facebook and Twitter, authors and publishers hope that these trailers will connect them with web-addicted demographics. To make them, some authors and publicists scout for talent among their friends, while others seek the paid assistance of production companies. But however they’re made, good book trailers are more than just a marketing tool — they’re art. “The web is providing so many exciting opportunities for video to live, and I think book trailers is one of those,” says filmmaker Scott Thrift of the Brooklyn-based video label m ss ng p eces.

This wasn’t always the case. When Thrift and his partner, Ari Kuschnir, first sat down with Random House to discuss making a book trailer for Robert Masello’s thriller Blood and Ice, they were taken aback by the shoddy production values of other trailers they saw. Says Kuschnir, “It would be something like a still photograph, and then the book would come flying in. Basically a glorified PowerPoint.” Still, they were excited by the opportunity to do something new with the medium, and were rewarded for their efforts in the end. In addition to being distributed widely online, their trailer was licensed abroad, and may even have a theatrical release in Portugal.

Because of their artistic bent, many book trailers are identified as short films “inspired” by a work of fiction or nonfiction. Sometimes they use voiceovers of an author reading from his or her book, with accompanying action. Actors in these films are usually friends, family, or people around the office at Random House or Penguin. Novelist Jami Attenberg appeared in her own conceptual book trailer for The Kept Man, created by a friend’s production company. The same company, Milk Products Media!, created a trailer for Sloane Crosley’s book of essays I Was Told There’d Be Cake, employing more non-narrative measures: stop-motion animation, finger puppets, and a catchy jingle. The video went viral, partly thanks to a nod on the New York Times Paper Cuts blog.

That’s the goal, says HarperCollins senior publicist Audrey Harris. She first oversaw a trailer in 2006, for Gregoire Bouillier’s The Mystery Guest. Book trailers were unusual then, but now they’ve become almost de rigueur, says Harris. She estimates that between 25 and 50 percent of Harper Perennial titles have trailers.

In terms of stylistic trajectories, Harris says animated trailers are the newest wrinkle. She oversaw one recently for Toby Barlow’s novel Sharp Teeth, created by a filmmaker friend, Eun Ha Paek. Neil Gaiman turned Blueberry Girl‘s illustrations into animation, adding a voiceover and an ethereal score of cricket chirps and wind chimes to make his trailer. Wells Tower read while an animated Viking ship bobbed in the ocean, illustrating the excerpt from his collection’s title story, “Everything Ravaged, Everything Burned.” And pencil drawings reminiscent of childhood are sketched before our eyes as Stefan Merrill Block reads from his debut, The Story of Forgetting.

Another class of book trailer works off of the public’s reaction to a book. The action in John Wray’s Lowboy takes place on the subway (Wraith also wrote large portions of his book in transit), so for his trailer, he had commuters on a Brooklyn L train read excerpts aloud. In a trailer for Much to Your Chagrin: A Memoir of Embarrassment, meanwhile, author Suzanne Guillette prompted strangers to reveal their own mortifying moments on camera.

Whether or not book trailers succeed as selling devices, it’s forming a meaningful connection with the public that’s important. As novelist Jami Attenberg puts it, “If somebody sees my trailer, they’ll know more about the book, and get an impression of me as an author.” Thrift and Kuschnir hope that soon, book trailers will be integrated into Kindle, to help convince online window shoppers to make a purchase.

When questioned about whether a trailer might corrupt how books engage the imagination, however — like seeing a movie adaptation before reading the original — Attenberg laughs aloud. “My trailer wasn’t taken from anything except a feeling, a moment, a little inspiration that grew. I would never let anyone use a promotional device that I didn’t feel reflected the spirit of what I’m doing. So, I’m not worried. I’m thrilled that it’s out there.”

Image: Still from “Everything Ravaged, Everything Burned” trailer