PHILADELPHIA - Coming soon to your TV: More advertising, in places you might not expect.

The ads are showing up where people used to enjoy a break from advertising, such as video on demand and on-screen channel guides. Even TiVo, which became popular for its technology that lets people skip TV commercials, is developing new ways to show ads.

As a result, you won't necessarily see more traditional, 30-second commercials. Instead, many of the new TV ads will resemble online ads - interactive and often shaped for individual members of the audience. They'll also be harder to ignore. Typically, you can't opt out of seeing them.

The companies behind the latest kind of ads hope they'll especially appeal to advertisers that are increasingly careful with their marketing budgets. In turn the advertisers are betting viewers won't be turned off - as long as the ads pitch products and services tailored to consumers' particular interests.

In a trial that ended last year in Huntsville, Ala., Comcast Corp. found that viewers shown targeted ads watched them 38 percent longer than folks who got less-relevant commercials.

"People like to shop. People like to research products," said Charlie Thurston, president of the advertising sales division at Comcast, the nation's largest cable TV provider. "Where advertising is intrusive is when there's a complete mismatch between product and viewer."

The increased advertising on pay TV services is striking, given that the industry started with scant ads as one way to appeal to subscribers.

Revenue from advertising on cable TV was just $100 million in 1981. By 2000, though, it hit $10.5 billion and then doubled this decade to $21 billion, according to research firm SNL Kagan.

To put this increase another way: There were 15 minutes and 30 seconds of advertising in the average hour of prime-time cable TV last year, up 14 percent from 1999, according to TNS Media Intelligence.

But that statistic doesn't account for advertising appearing in new formats on your TV.

For instance, Time Warner Cable Inc. is layering another ad on top of a TV commercial in order to keep the viewer engaged past the 30-second spot. In several markets, Time Warner Cable subscribers watching a Big O Tires commercial might see a banner from the company pop up at the bottom of the screen, telling them to push a button on the remote control for more information. Then pushing another button would let them request a coupon in the mail.

TiVo, the creator of the digital video recorder that panicked the TV business by making it simple to skip ads, now flashes banners on TV screens when users pause, fast-forward or delete shows.