PayPal has developed a behavioral tracking platform on Hadoop to understand customer behavior across its 110 million accounts. The platform collects metadata on customer interactions and sessions across channels. It uses a entity-event data model and performs attribution, sessionization, and metrics generation to provide insights. PayPal analyzes the data using Pig scripts to calculate metrics and dimensions like visitors, sessions, page views by page and browser. This helps PayPal improve customer experience and drive outcomes.