Facebook Ads Will Follow You Around

Good news for advertisers, but maybe not-so-great news for users concerned about their personal data: Starting Monday, Facebook will use data it gleans from users for its new ad network, Atlas, which it will serve up ads on non-Facebook sites based on what Facebook knows about you.

Atlas is a former Microsoft property that Facebook bought last year for around $100 million that Facebook has now rebuilt from the ground up. Atlas is distinct from Audience Network, a mobile ad network Facebook introduced in April that was aimed at app developers.

In contrast, Atlas is a sort of alternative to Google's AdWords, which will let advertisers follow users across the web and mobile devices. For instance, Atlas advertiser Pepsi could use Atlas to advertise one of its products on a sports site or a game app that is unaffiliated with Facebook.