Proof of Work was originally invented as a measure against spam.

Proof of Work requires a computer or user to solve a difficult task to satisfy set requirements.

The concept was initially created to prevent email spammers from sending disproportionate amounts of emails to many users.

The RPoW token was the first use case for Proof of Work, which could be used once and then exchanged for a new token.

RPoW became a prototype for digital cash in line with Nick Szabo’s theory of collectibles.

RPoW was a precursor to Bitcoin and its Proof of Work consensus mechanism.

Bitcoin Whitepaper provides a more detailed explanation of how Proof of Work is applied in the Bitcoin network.