Axon is a lightweight framework that supports the implemenation of CQRS patterns by providing commonly used building blocks. One of those patterns is an event sourced application architecture. Even though Event Sourcing and CQRS are orthogonal concepts they fit together very well and are often used together. Event sourcing in an ES/CQRS architecture means that all changes to the application state are done via domain events and the current state can always be rebuilt from the series of events available in a persistent event store. In addition to the event store there might also be one or more read models, for example to achieve opimtized query performance. No matter if there are read models or not, the event store is considered the single source of truth.