Event sourcing is a powerful pattern that can fundamentally change how you approach building applications, when auditability and adaptability are needed. However, aspects of event sourcing can be misunderstood, and those misconceptions make it harder to understand and utilize effectively. We'll take away the abstractions and focus on building an event sourced system without the use of an event sourcing library. This approach will help focus on the core concepts: what an event table is, how events are replayed when loading an aggregate root, what a projection is, and how snapshots work. Once we've established that base understanding, we'll take a look at how event sourcing libraries handle common concerns. Along the way, we’ll clear up some common points of confusion, and explore how this can be applied to existing systems, not just greenfield projects. You’ll leave with a clear foundational understanding of event sourcing, so you can decide if this pattern is right for your next project.