• by Mark Walsh  @markfwal, May 20, 2013

Yahoo on Monday confirmed it will buy blogging service Tumblr for $1.1 billion in cash.

The deal is by far the company’s largest since CEO Marissa Mayer came on board last July to reverse the company’s sagging fortunes and revive growth. Under the agreement, and its “promise not to screw it up,” Yahoo said Tumblr will be independently operated as a separate business, with founder David Karp remaining as CEO.

Through their combination, Tumblr would be able to use Yahoo’s personalization and technology and search capabilities to help users discover content, while Tumblr’s 50 billion blog posts would help expand Yahoo’s media network, the companies said.

"Tumblr is redefining creative expression online," said Mayer, in a statement. "On many levels, Tumblr and Yahoo couldn't be more different, but, at the same time, they couldn't be more complementary. Yahoo is the Internet's original media network. Tumblr is the Internet's fastest-growing media frenzy.”

For his part, Karp said Tumblr would get better faster, "with more resources to draw from."

The transaction, which had been rumored since last week, is expected to close in the second half of the year.