Currently, Facebook ads are targeted based on users' profiles and the companies or other pages they "like."

Story highlights

Facebook Exchange will use Web browsing to target ads

Browser cookies will let advertisers hyper-focus their offers

Facebook says users may opt out of the ad model

"Real-time bidding" is already used by Google, others

CNN  — 

Facebook will soon be using your Web browsing to help decide which advertisements you see.

A new Facebook system will use your activity on other websites to send you what Facebook thinks are ads about your current interests. Advertisers will, in effect, be bidding to get their ads in front of you.

Here’s an example: Say a Facebook user visits a travel website and clicks on a page about a vacation package to Las Vegas. If an advertiser has bid on that kind of search, that user could then see ads for discounted trips to Vegas the next time they visit Facebook.

“By bidding on a specific impression rather than a larger group, advertisers are able to show people more relevant ads while also running more efficient and effective campaigns,” a Facebook spokeswoman said in a written statement.