In the layman language, a Blockchain is a public distributed ledger in which the information is stored in the form of small blocks and each block is connected together to form a blockchain. The information is recorded and verified by each node for preventing the tampering of data. Blockchain technology was invented in the 1990s but it was actually used in 2009 for the production of cryptocurrencies (Bitcoin). Later, the same technology was used in other fields as well such as banking, transactions, healthcare, digital ID, etc.
A Blockchain contains three parts:
Hash is the unique code assigned to any block. All the blocks are identified by their unique hash value. If the information is tampered with or changed, the hash value of the block changes.
Hash of the previous block:
Each block contains the hash value of the previous block. It helps in building the blockchain.
The information/data that is to be stored in the block. Once the information is stored in the block, it does not change. But if someone tries to change the information, the hash value of the block changes.