Based on the event sourcing concept, such stores are used to keep time series records of all events that change the state of an individual object. This is what makes them different from other types of database management systems, where only the current state of an object is stored.
Event stores support such manipulations as the insertion of new events and querying event time series for an object. However, modifications or deletions of existing events are not possible. The feature is of special value for distributed systems, where consistency is very important.
Examples of event stores are Event Store and NEventStore.
