Yahoo! on Monday said it has bought a freshly launched startup that lets television viewers instantly share what they are watching with friends at Twitter or Facebook.

Yahoo! did not disclose how much it paid for IntoNow, which launched on January 31 in the Silicon Valley city of Palo Alto, California.

"We were all surprised to say the least but it makes a ton of sense and we're ready to rock," IntoNow's seven-member team said in a blog post at the startup's website.

IntoNow offers a free software application that lets iPhones identify television shows being watching and then share the information at popular social networks Facebook or Twitter.

Sunnyvale, California-based Yahoo! has been reinventing itself as a digital media company after being eclipsed by Google in the online search market.

The transformation includes Yahoo! Connected TV software built into television sets to link viewers to online content.

IntoNow built a platform that not only lets people "check-in" online within seconds to shows they are watching but indexes related episodes dating back five years.

"IntoNow has built a unique way for people to engage with each other around the content they enjoy," said IntoNow chief executive Adam Cahan.

"Companion applications and devices are changing the way we interact with TV in significant ways."

Yahoo! planned to use IntoNow technology to enhance online media and video offerings and to make its services more social.

IntoNow's application is integrated with Facebook, Twitter, Apple's online iTunes shop, and US online video rental giant Netflix.

"Relying on social channels as a means for discovering content -- whether it's on a PC, mobile device, or TV -- is rapidly on the rise," said Yahoo! senior vice president of product management Bill Shaughnessy.

"The IntoNow application the team has built clearly demonstrates the opportunities the technology presents across Yahoo!'s network, especially in regards to our video content, search, mobile and Connected TV experiences."