The security posture of an application is directly proportional to the amount of information that is known about the application. Although the advantages of analytics from a data science perspective are well known and well documented, the advantages of analytics from a web application security perspective are neither well known nor well documented. How can we, as web application security practitioners, take advantage of big data stacks to improve the security posture of our applications? This talk will dive into the ways that big data analytics can be taken advantage of to create effective defenses for web applications today. We'll outline the fundamental problems that can and should be solved with big data and outline the classes of security mechanisms that simply, based on their nature, cannot be solved with big data. Once an understanding of the domain is established, we'll explore several specific examples that outline how one security team uses big data every day to solve hard, interesting problems and create a safer experience for its users.