Google says mobile advertising has "enormous potential"
Google, the world's most popular search engine, has agreed a deal to buy the mobile advertising firm AdMob.
It is paying $750m (£449m) in stock for the firm in a bid to take advantage of opportunities in the booming market for mobile devices.
AdMob specialises in selling adverts displayed on small screens - for example the iPhone or the Blackberry.
Google said mobile advertising had "enormous potential" and praised AdMob's "exceptional progress".
"AdMob is the quintessential Silicon Valley start-up, generating impressive year-on-year revenue growth, and we're excited to welcome this talented team to Google," said Susan Wojcicki, Google's vice-president of product management.
The new partners will now look to use new mobile technology to drive mobile advertising.
"I think people underestimate how important ads have been to funding the development of innovative content on the internet," said AdMob founder Omar Hamoui.
"Our goal has been to make it possible for developers and publishers to bring their products and ideas to mobile with the same business model."