Replication
Replication is a mechanism for synchronizing content in multiple copies of an object (for example, the contents of a database or blockchain). This is the process of copying data from one source to another (or to many others) and vice versa.
During replication, changes made to one copy of an object can be propagated to other copies.
Blockchain as a replicated distributed database
Blockchain is a replicative state machine.
State means "stored information" at a certain point in time. A state machine is a computer or device that remembers the state of something at a given time. The status of the data is changing, and the blockchain as a state machine ensures that changes are made to all copies.
Tracking the transitions of these states is important, and it is the blockchain that also copes with this. Simple databases do not do this, since they are not protected from unauthorized access, and in the blockchain, the history of the transition from state to state is a constant and important part of the information.