Blockchains are innovative solutions for storing transaction-related information. Blockchain technology gets its name from the fact that records are stored in blocks of data that are linked together to form a chain. What makes a blockchain immutable, meaning that it cannot be altered, is the fact that each transaction record is directly linked to the previous one using advanced cryptography. The encryption that blockchain technology relies on is one of its strongest security features.
Each entry on a blockchain is encrypted into a hash — i.e., a string of letters and numbers of a fixed length. When a new transaction record is added to a blockchain, both the previous transaction and the new one are run together through the cryptographic formula to generate a brand-new hash. This process continues indefinitely — and because each new record is dependent on the previous one, records cannot be altered without breaking the formulas or the protocol.