It all started shortly after the 2008 global financial crash, a whitepaper was introduced by a person or group calling themselves Satoshi Nakamoto. In this whitepaper, a new peer to peer financial system was discussed. Concept of digital currency Bitcoin was mentioned in the whitepaper.
In start it was hard for people to understand the concept behind the digital currrency but gradually they started to accept the fact that this system is better than the old one. This new system was named Blockchain.
Blockchain is simply a underlying technology behind bitcoin and ethereum, but its uses go far beyond that. In simple words blockchain is a continuously updated record of who holds what. These records are split into linked blocks, and then secured using cryptography. The cryptography part just means that you can be sure about the records. This is dubbed as automated trust, or trust that's inherently build into the system. the list of records is decentralized and it is available to everyone to see and verify.
The best part about the blockchain is that it is almost impossible to hack the blockchain because of its distributive nature. Everyone will know that the block has been messed with and it will be rejected by everyone who is part of the system.
Image Source : https://medium.com/swlh/dont-buy-the-blockchain-hype-3eae869e2de0
