Reality is event-sourced; your mind processes sight, sound, taste, smell, and touch to create its perception of reality. Software isn't that different. Applications use streams of incoming data to create their own realities, and when you interpret that data as events containing state and context, even some of the most complex problems become easily solvable. Unravel the theory behind event sourcing and discover how to put this approach into practice with practical, hands-on coding examples. From early-stage development through production and release, you'll unlock powerful new ways of clearing even the toughest programming hurdles. Our applications are bombarded with data. It's hard enough to derive state from that data, let alone discover how we arrived at that state. With event sourcing you can treat the stream of data as a simple sequence of events that you use to construct whatever state you need. Event sourcing is more than events; it adds patterns, rules, and constraints to produce robust and easy-to-maintain systems. In this book, you'll learn which rules can never be broken and which ones are flexible. By grounding yourself in theory, rules, and practical approaches, you'll be able to build real-world, event-sourced applications. Get your hands dirty with fundamental event-sourcing building blocks such as commands, aggregates, projectors, process managers, injectors, and notifiers. Combine these building blocks to produce elegant solutions to complex problems. Leave "hello world" far behind as you tackle the more advanced aspects of event sourcing that give you the confidence you need to run these applications in production. Leverage event sourcing to create distributed applications with ease; model and handle failure; and deal with replays, schema evolution, security, and much more. This book doesn't shy away from confronting the hard parts of event sourcing, instead giving you clear advice and examples for tackling the most difficult details. Empower your applications with the full force of event sourcing today. What You Need: You'll need a computer preferably running MacOS, Linux, or WSL/Ubuntu on Windows. You'll install everything else you need (such as Elixir and an event store) as you progress through the book.