"At a certain level of abstraction, all complex systems are message passing systems." - Grady Booch. In software, we are often passing messages around between components, services and even systems. We do so in synchronous and asynchronous ways. The second half of Grady's tweet talks about how societies use memes to pass information across time. In software, we use the state of our system to do the same: everything we write to storage is, in essence, a message for our future system.

If we use Event Sourcing as our persistence pattern, we are making this message passing in time much more explicit in our software. And there are other benefits too! For instance, we are sacrificing a lot less information compared to classical relational databases. We also enable point-in-time capabilities for our entities. And we are much more likely to be able to fulfill future business requests based on old data.

Does that sound complex? It doesn't have to be. In this talk, I will given an introduction to what Event Sourcing is, how to fit it into a CQRS architecture, and what design patterns you can use to unlock its full potential.