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CBS said Thursday it is launching a digital subscription video service that includes live streaming and video on demand.

The announcement marks the latest in a string of developments shoring up the concept of Internet-based TV as a growing competitor to traditional television. On Wednesday, HBO unveiled plans to launch a standalone service next year that will let people watch programming purely online without subscribing to any pay-TV provider, and companies including Verizon, Dish and Sony are aiming to fire up online-only multichannel video services this year or next.

The service, called CBS All Access, is priced at $5.99 a month and is untethered to any pay-TV subscription. It will offer thousands of episodes from the current season, previous seasons and classic shows on demand, as well as the ability to stream local CBS stations live in 14 of the largest US markets at launch, the company said. (CNET is owned by CBS Interactive, a unit of CBS.)

Although broadcast rival ABC, owned by Disney, was the first out of the gate in providing a live-streaming feed of its programming in certain markets, it stuck to the TV industry's favored format of offering the service only to people who already subscribed to a pay-TV like cable or satellite. CBS breaks from that mold, allowing anyone to sign up for the new offering.

The riskiness of breaking a digital video service out of the normal pay-TV system is lower for a broadcast network like CBS than it is for a cable channel like HBO. Though almost all traditional TV is watched via a pay-TV subscription like cable or satellite today, broadcast networks were -- and still are -- free for anyone to watch over public airwaves.

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Still, it's a bold move for CBS, which is perhaps best-known in the Internet TV world for being an opponent rather than a cheerleader. CBS was an outspoken adversary against Aereo, the startup that streamed over-the-air TV signals to its paid subscribers without handing royalty or carriage fees back to license holders like CBS. Broadcast television companies including CBS sued Aereo, and the Supreme Court ruled this year that the service was essentially illegal in its current form. The case was sent back to a lower court, where it is still pending.

But CBS has been innovative with digital platforms in other ways. A deal with Amazon last year licensed episodes of the CBS summer series "Under the Dome" to the e-commerce giant five days after they were broadcast, a partnership the companies extended this year and expanded to the Halle Berry sci-fi thriller "Extant."

On Thursday, Jim Lanzone, president and CEO of CBS Interactive, said that the company has integrated the CBS All Access service into existing offerings like CBS.com and the CBS app and that All Access will come to all major digital platforms - including additional connected devices -- in the coming months

"Our focus is to develop the best cross-platform video experience possible," Lanzone said in a statement. "CBS All Access delivers on that promise by giving our audience not only more CBS content but also more ways to watch."

CBS All Access will have full current seasons of 15 prime-time shows with episodes available the day after they air, in addition to live-streaming of 14 local stations. It will also have full past seasons of eight current series like "The Good Wife," "Blue Bloods" and "Survivor" and a library of more than 5,000 episodes of CBS classic programs like "Star Trek" and "Twin Peaks," and the several series belonging to the "CSI" franchise.

Classic shows will be ad-free. The more current content will include commercials, and live-streams will have the advertising that is already programmed into the broadcast itself.

UPDATED at 6:20 a.m. PT and 6:32 a.m. PT: To add context and further details.