Blockchain is a distributed ledger technology that enables the creation of a digital ledger of transactions that is duplicated and distributed across the entire network of computer systems on the blockchain. Each block in the chain contains a number of transactions and every time a new transaction is added, it is added to the most recent block. Once a block is added to the blockchain, the data in it cannot be altered or deleted, creating a permanent and unchangeable record.

One of the most well-known and widely used applications of blockchain technology is in the creation of cryptocurrencies such as Bitcoin. Blockchain technology enables the creation of a decentralized, digital currency that is not controlled by any government or financial institution. It also allows for secure and transparent transactions without the need for a central authority.