"Event-driven" has already evolved to the level of a magical buzzword in IT marketing and sales activities. But the list of tech concepts behind that term is long. This talk walks you through the entire "event land" and explains what is what, so the next time you face the "event-driven" label, you can ask the right questions and make educated choices. Then it shows how events prevent your applications from recklessly losing precious information they had in the past. It also presents solutions that remember its entire history. It demonstrates what it takes to build such in Java. The takeaway from the talk is an applicable mental model of Event Sourcing, DDD, and CQRS concepts working together to achieve business goals.