Facebook Inc. is launching a new type of mobile advertising that targets consumers based on the apps they use, pushing the limits of how companies track what people do on their phones.

The social network is tracking the apps that people use through its popular Facebook Connect feature, which lets users log into millions of websites and apps as varied as Amazon.com, LinkedIn and Yelp with their Facebook identity. The company then targets ads based on that data, said people familiar with the company's plans.

Facebook...