This document discusses real-time decision engines and how they can react to business events in real-time. It provides examples of how real-time decision engines work in different industries like telecommunications, banking, insurance, and media. Real-time decision engines integrate real-time data sources to understand customer context and trigger actions in response to events. They are built using a microservices approach and streaming data technologies. Examples of applications include real-time marketing, fraud detection, content recommendations, and enforcing business rules.