Blockchain is a decentralized digital ledger technology that securely records transactions across multiple computers, ensuring that the data cannot be altered retroactively without altering all subsequent blocks and gaining consensus from the network. Each block contains a list of transactions and a unique code called a hash that links it to the previous block, creating a chain of blocks—hence the name “blockchain.”

Functionally, blockchain operates through a distributed network of nodes, each holding a copy of the entire blockchain. When a transaction occurs, it is broadcast to the network, and nodes validate the transaction using a consensus mechanism, such as Proof of Work (PoW) or Proof of Stake (PoS). Once verified, the transaction is grouped with others into a block, which is then added to the chain in a linear, chronological order. The use of cryptographic hashes ensures the integrity and security of the data, as any attempt to alter a single transaction would require changing the hashes of all subsequent blocks, an almost impossible task given the computational power required.

Blockchain’s decentralized nature eliminates the need for a central authority, reducing the risk of data tampering and fraud. It is widely used in various industries, including finance, supply chain, and healthcare, for its transparency, security, and immutability.