Hash Function
A specific algorithm that maps data of any size to a fixed size output, also referred as a cryptographic function since they are often used for encryption and other security purposes where it cannot be reversed through computation alone; hashing takes an inputted string/file/document and outputs the same thing every single time so long as its original content has not been altered even if just by one letter or space character. This process is irreversible, making working backwards to discover what was used next nearly impossible unless someone had access to the private key associated with each transaction on blockchain networks containing these hashes written into their blocks instead. Every cryptocurrency's hash algorithm must meet certain requirements before being approved into existence.