When people create profiles on platforms such as Facebook, Twitter, Amazon or Pandora (or even digital television services like FioS), the information they volunteer about themselves is connected to an identifier (ID) unique to them. The ID, when a user is logged in, is constant across numerous devices. Marketers can use the vast about of information associated with an ID to create advanced audience segmentations, deliver more relevant messaging across devices and understand how their campaigns influence a consumer’s path to purchase. Browser tracking cookies are increasingly unreliable — on desktops and in mobile web browser environments, and all but useless in mobile apps. That’s why, as people interact with and consume media across multiple devices, web targeting and tracking methods using logged-in user data have become more important. Marketing that relies on logged-in user data often is referred to as a deterministic approach.