The "21 Million Club" is a colloquial term within the cryptocurrency space, specifically associated with Bitcoin. It refers to the predetermined maximum supply of Bitcoin, capped at 21 million coins as per the Bitcoin protocol.
Bitcoin, often referred to as "digital gold," is the first decentralized cryptocurrency created by a person or group of people known as Satoshi Nakamoto. Operating on a peer-to-peer network without the need for intermediaries, Bitcoin enables secure and transparent transactions that are recorded on a public ledger known as the blockchain.