What is event sourcing?
Event sourcing is a way of persisting your application's state by storing the history that determines the current state of your application. For example, a conference management system needs to track the number of completed bookings for a conference so it can check whether there are still seats available when someone tries to make a new booking.
It could store all the booking and cancellation events for each conference and then calculate the current number of bookings by replaying the events associated with the conference for which you wanted to check the current total number of bookings.
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