In the simplest of terms, Blockchain is a time-stamped series of immutable records of data that is managed by a cluster of computers not owned by any single entity. Each of these blocks of data (i.e. block) is secured and bound to each other using cryptographic principles (i.e. chain).
So, what is so special about it and why are we saying that it has industry-disrupting capabilities?
The blockchain network has no central authority - it is the very definition of a democratized system. Since it is a shared and immutable ledger, its information is open for anyone and everyone to see. Hence, anything that is built on the blockchain is by its very nature transparent, and everyone involved is accountable for their actions.