Blockchain

Cryptography is a direct link to the blockchain world. A blockchain is resistant to modification of the data and it is an open distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way. If simply understood, it is a growing list of records called blocks. And each block is a cryptographic hash of the previous block, a timestamp and transaction data.
Blockchain was invented by a group of people called Satoshi Nakamoto in 2008 to serve as a public transaction of cryptocurrency bitcoin. The identity of that group called Satoshi Nakamoto is still unknown. The invention of blockchain in reference to bitcoin made it the first currency or digital currency to solve the double-spending problem without a need of a trusted authority or central server. Blockchain is also considered as a payment rail.
There is no security in this chain, so some time computer world marketing also called it snake oil.