The Zcash protocol is a set of rules that govern the Zcash blockchain network, a system of connected devices all over the world, working together to validate transactions and maintain the Zcash ledger. Within that system, ZEC (pronouced zek) is the monetary unit, or coin. You can send ZEC to a friend, use it to purchase something, or exchange it for some other kind of money. Zcash monetary policy creates a currency supply of 21 million ZEC. If a person holds 5 units of Zcash, then they hold 5 ZEC.