HashCash

What is HashCash?

HashCash is a cryptographic proof-of-work system that was created in 1997. It was initially designed as a spam control mechanism for email systems, but later became an important technology for the development of the blockchain. HashCash works by requiring the sender of an email or a blockchain transaction to perform a certain amount of computational work, which acts as proof that the sender is a real person and not a bot. This proof-of-work is done by solving a mathematical puzzle, which involves generating a value that satisfies certain cryptographic conditions. The solution to this puzzle is included in the header of the email or transaction and acts as proof that the sender has invested the required computational effort.