Distributed Ledger Technology defines a consensus-based, replicated, shared, and synchronised record-set, not bound to a single location, and therefore without a central administration or data storage. Blockchain is a form of DLT.
What this means is that anyone can have a copy of the database, and each person’s copy should be identical. There is no master copy, and it is solely through a common agreement that each copy of the database can be considered genuine.