What is blockchain? Blockchain is a specific type of database with special data organization and properties.
Blockchains store data in blocks that are then cryptographically chained together in the chronological order one by one, with the block chained onto the previous block.
Data commonly stored in blockchains are transactions for Distributed Ledgers. The transactions are chained together following the blocks which store the data.
Transactions in blockchains are cryptographically signed by the users so that no other person or organization can forge transactions.
The blocks in a blockchain are synchronized across blockchain nodes connected through peer-to-peer networks and protocols.
Blockchains are usually deployed and managed in decentralized ways through Decentralized Consensus Mechanisms such as Proof-of-Work (PoW) and Proof of Stake (PoS). No single person or organization has control-rather, all users and blockchain node maintainers collectively retain control using consensus protocols.
Transactions are immutable and irreversible in decentralized blockchains once the transactions are included in blocks broadcasted to the blockchain network and accepted by the majority of the blockchain network nodes.
Blockchain is the basis of some use cases. Killer applications on blockchains include Cryptocurrencies and NFTs. Blockchain networks are commonly used for hosting the ledger for Cryptocurrencies. It is common that many blockchains have their native platform cryptocurrency (coin).