A hash links one block to another. This is done by mathematically using an encrypted hash. The hash in a blockchain is created from the data of the previous block. The hash consecutively bonds one block to the next based on time order. Hashing was invented over 30 years ago. A hashing function creates a mathematical algorithm that maps data of any size to a bit string of a fixed size. A bit string is usually 32 characters long, which then represents the data that was hashed. The Secure Hash Algorithm (SHA) is one of some cryptographic hash functions used in blockchains. SHA-256 is a common algorithm that generates an almost-unique, fixed-size 256-bit (32-byte) hash. A simple way to think of a hash is as a digital fingerprint of data that locks it in place within the blockchain.
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