Event sourcing is an architectural pattern in which every change to an application’s state is recorded as a sequence of events (Fowler, 2005). Event sourcing is a companion architecture to domain-driven design, with events related to aggregate root entities within the domain. In domain-driven design, we model the domain by creating a ubiquitous language that captures its core concepts. Those objects are subject to certain actions, and it’s natural to think of these actions as events that have occurred.