1. Miners work on validating “blocks” of recent transactions. Blocks are pages in the global ledger book tracking all transactions.
2. To make it hard for fraudsters to submit false verifications, Bitcoin makes it hard for everyone: to finish a block, you must complete a puzzle. Miners pick an arbitrary number, called a “nonce”.
3. When the transactions and the nonce are put through a certain unpredictable, irreversible function, it spits out another number, called a “hash”, like 0a8ce26f.
4. The first small-enough hash wins the block, and its 25 Bitcoin ($21,000) reward. The block is added to the “blockchain”, the official record of every Bitcoin transaction ever. (The first-ever Bitcoins were mined in the genesis block.)

• Blocks mined: 0
• Hash success probability: 12.5%
• Miners bought: 0

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