What does eventual consistency mean in the context of CQRS, and why does it happen?

Eventual consistency means that after a write happens on the command side, there's a brief window during which the read side hasn't caught up yet, because it's updated by reacting to changes from the write side rather than updating in the exact same instant. A user who creates a loan and immediately refreshes a dashboard reading from the query side might briefly see stale data until the read side finishes processing the update. This isn't a bug or a sign of a broken implementation — it's a direct, unavoidable consequence of having two separate models updated at two separate points in time. Systems that genuinely cannot tolerate any staleness at all are a signal that CQRS may need careful extra design work, or may not be the right fit for that particular part of the system.