All terms
A fixed length fingerprint of any piece of data.
A hash function takes any input and produces a fixed length output. Change one character of the input and the output changes completely and unpredictably. You cannot work backward from a hash to the original data.
Blockchains use hashes everywhere: to link blocks together, to identify transactions, to commit to data without revealing it, and in proof of work to make mining costly.
Bitcoin uses SHA-256. Mining is the search for an input whose hash starts with a certain number of zeros.
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