What is the Event Sourcing Pattern?

Event Sourcing stores the state of a system as a sequence of state-changing events, rather than just storing the current state.

Instead of updating a database record, you append an event (e.g., OrderCreated, ItemAdded, OrderShipped). The current state is derived by replaying these events. It guarantees a 100% reliable audit trail and allows temporal queries (state at a point in time).