A Blockchain is a decentralized, distributed and a public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the collusion of the network.
The Blockchain was invented by Satoshi Nakamoto in 2008 to serve as the public transaction ledger of the cryptocurrency bitcoin. (as explained in Wikipedia).
Blockchain technology can be used for wide variety of applications such as tracking ownership or the provenance of documents, digital assets, physical assets or voting rights.
By design, the blockchain is a decentralized technology. This Blockchain technology also provides enhanced security methods, such as by storing data across its network, the blockchain eliminates the risks that come with data being held centrally.