The comic book industry makes a long-delayed step into cyberspace today when Marvel Comics unveils the industry's first online archive of more than 2,500 back issues, including the first appearances of Spider-Man, the X-Men and the Incredible Hulk.

Marvel Digital Comics Unlimited will offer the archive in a high-resolution format on computer screens for $59.88 a year, or at a monthly rate of $9.99, at marvel.com.

Subscribers will be able to access the first hundred issues of key titles, turn pages with a click of the mouse or navigate a battle against Dr. Doom frame-by-frame with a "Smart Panel" viewing feature. The user can zoom in on details of art by Jack Kirby and Steve Ditko from the 1960s or catch up with today's The Ultimates and New Avengers.

"We did not want to get caught flat-footed with kids these days who have the tech that allows them to read comics in a digital format," says Dan Buckley, Marvel's president. "Our fan base is already on the Internet. It seemed like a natural way to go."

To help sell the experience to an audience unaccustomed to paying for content, Marvel will offer a free sampler of 250 titles. Asked why people would pay for superheroes when newspaper websites have been unable to charge for content, Buckley says, "You can get the news anywhere. We're the only ones who have Spider-Man."

While comic book publishers have experimented with online content for years, Marvel's effort is by far the most extensive. DC Comics recently launched its own online site, Zuda comics.com, which offers free online comic strips by newcomers. DC does not offer its back catalog of Superman and Batman online.

Marvel's online initiative comes as publishers find that the traditional comic book, which now costs $2.99 an issue, is acting as a springboard to other formats, including trade paperbacks and more expensive reprints.

To protect current sales of comic books, new issues won't be on the Marvel site until six months after they are published.

"If they put their monthly comic online at the same time, they'd be cutting their own throats and undercutting the retailers," says Peter David, a comic book writer currently adapting Stephen King's The Dark Tower for Marvel. "The material is owned by Marvel, and they can do whatever they want with it. This is just another means of reprint when you come down to it."

Comic books have not been immune from Internet file sharing. But unlike MP3s for music, fans haven't found a format to easily share the pages.

"About 90% of the comic books sold today are scanned and put online within 36 hours," says Chris Arrant, a comic book analyst for Newsarama.com.

"Our quality is much higher; the library is huge and will never go out of style," says Marvel editor in chief Joe Quesada. "This is the legal way to do things."