Blockchain refers to a distributed digital ledger of cryptocurrency transactions. The name is in fact based on the technology that runs the framework. This technology involves the addition of individual transaction blocks onto a growing chain for recordkeeping.
A distributed ledger is simply a database that is shared within a network and synchronized. Every participant on the different nodes of the network has access to the shared record. All amendments made to the record are instantly shared on all the nodes.
The database is immutable and unalterable. Every block added to the chain contains a batch of time-stamped transactions that once verified, cannot be reversed. Every one of these blocks has a unique cryptographic signature. Its signature links back to the previous block on the chain and in this sense the chain is fully back-linked to the original block.