Google and Facebook announced a detente of sorts on Friday in which Google will sell Facebook ad inventory.

The ads will be sold via Google's DoubleClick Bid Manager, its real-time bidding system. In a few months, marketers will be able to buy ads for Facebook's Ad Exchange on the platform.

"Partnership has been key to Google’s success as a rising tide lifts all boats. So we’re excited to announce a new way to help our clients succeed by working with Facebook to participate in FBX, their real-time bidding exchange," Payam Shodjai, Senior Product Manager at Google, wrote in a post.

Facebook introduced FBX last year. The program lets advertisers drop cookies in users browsers and then retarget those users when the re-enter Facebook.

Though Facebook and Google compete on many levels, their partnership isn't unprecedented. In June 2012, Google bought Wildfire, a social media marketing agencies that develops ad campaigns for Facebook, among others. Facebook this year also purchased Atlas, an ad server that sells ads on Google's display network.

Bonus: The Evolution of the Facebook Profile

The Evolution of the Facebook Profile

Image: Getty/Lionel Bonaventure