Today Facebook launched the Audience Network, its new ad network for mobile apps. Here's what that actually means: starting today, you're going to see "Facebook ads" inside the free apps you use. Today, those tiny, often-annoying annoying banner ads might be provided by Google, Flurry (Yahoo), or MoPub (Twitter). From now on, many of them will be provided by Facebook. And since Facebook knows a lot more about you than many of these companies, the ads you see inside apps might get creepier — or "more relevant." It's all about how you look at things.

• Advertisers can't purchase ads inside third-party apps like Flappy Bird. They can only "extend" current Facebook ads, which show up inside Facebook on the web and mobile, into other apps.
• Shazam is an early pilot tester of Audience Network. You might have already seen some Facebook ads inside the app. They don't look much different from other banner ads.
• Audience Network ads might also take the form of "native content" inside news apps like The Huffington Post.
• Facebook wants a big piece of the $140 billion digital advertising market. Audience Network will likely prove to be a massive new revenue stream for Facebook, which is rapidly expanding its reach beyond Facebook proper. Atlas, announced last week, lets advertisers use Facebook's knowledge of its user base to place ads on other websites.