A blockchain is a digital ledger which works in a decentralised manner facilitating transactions and tracking assets in an immutable ledger and data entry cannot be reversed. The transactions are saved in a chain of blocks.
Blockchain uses digital signatures in the form of a public key/private key pair, that are commonly used to enable the identification of a participant part of the transaction. In a proof-of-work model, the computing power needed to support the distributed ledger is generally provided by the users/miners, who are often paid small amounts of the applicable cryptocurrency for their efforts.
The decentralisation of data transportation and administration, as well as digital representations of assets or other value, is enabled by blockchain technology. More specifically, blockchain technology enables the authentication and settlement of transactions without the use of centralised intermediaries or authorities. This is due to the distributed nature of a blockchain. It also has the ability to enable trustable transactions between computers through a distributed consensus mechanism.