SHA-256

A hash function used in Bitcoin and other blockchains to secure transactions. The hash is done by inputing any length of characters into the SHA-256 protocol. The protocol will then generate an output string of exactly 256 bits. So any amount of data can be contained within the hash, but the SHA-256 will remain the same. Also, any change to the input data would result in a change to the output. The same output can never be derived from different inputs. It is a one-way function since you can never determine the inputs by output (which is the hash).