A blockchain is a decentralized and distributed digital ledger that is used to record transactions across many computers in a secure and transparent way. The name "blockchain" comes from the way the data is stored in the ledger, which is broken down into blocks that are linked together in a chain-like structure.!
Each block in the chain contains a set of transactions, and once a block is added to the chain, it cannot be modified or deleted. This makes the blockchain a tamper-evident and tamper-resistant database.
In a blockchain, each computer or node in the network has a copy of the ledger, which is constantly updated as new transactions are added. To add a new block to the chain, a consensus mechanism is used to ensure that all nodes in the network agree on the validity of the new block. This consensus mechanism varies depending on the blockchain, but it is typically based on proof-of-work (PoW), proof-of-stake (PoS), or a combination of both.
These are just a few examples of the many different types of blockchains that exist. Each blockchain is designed to serve a specific purpose, and they all have their own unique features and characteristics.