So how do you keep millennials coming back to your business? Pay them. 

That's the idea behind Tumblr's latest monetization strategy. Starting today, the social media network, which Yahoo acquired for $1.1 billion in 2013, is allowing brands to advertise on its platform. The ads will appear in three places--a blog's main page, right sidebar, and on mobile. They'll also show up on default, requiring users who don't wish to participate to manually opt out.

Tumblr's largely millennial audience operate roughly 307 million blogs on the platform. And while these mostly artists and writers might chafe at the thought of having ads served up on their blogs, the idea is to one day pay them for the imposition. 

Later this year, the company plans to release details on how bloggers can get a cut of the ad sales, which it says should be an incentive for many to allow the ads to stay.

The move marks a departure for Tumblr which has been slow to generate revenue. Previously, the company's only income stream was native advertising which, since its acquisition by Yahoo, has fallen short of expectations--coming in under its $100 million target in 2015. 

Naturally, the company is looking to remedy this--particularly as Tumblr's parent company, Yahoo, was just acquired by Verizon for $4.8 billion. Indeed, "there's a lot more to come," Karp writes on his Tumblr page.