How Crypto WorksA VISUAL FIELD GUIDESearch
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ROUTE 05 / Start here

From a key to Bitcoin

Connect signatures, unspent outputs, mining, and confirmations.

5 ideasAbout 25 minutesRead in order, or choose a step

Bitcoin combines several mechanisms into a shared ledger without a central account administrator. Each piece solves a different problem. Hashing detects changes, signatures authorize spending, and proof of work helps resolve competing histories.

  1. 01

    Private keys, public keys and addresses

    Start with authorization

    Keys enable control over spending conditions.

  2. 02

    UTXOs and change outputs

    Locate the spendable outputs

    Transactions consume previous outputs and create new ones.

  3. 03

    Cryptographic hashes

    Make changes detectable

    Hash links commit to data; they do not keep it secret.

  4. 04

    Proof of work

    Add costly evidence

    Work makes proposing a competing history costly under the consensus model.

  5. 05

    Bitcoin as a complete system

    Assemble the system

    Separate the network, BTC units, wallets, and the market price.

CHECK YOUR UNDERSTANDING

Does a valid signature guarantee that the same output was not spent elsewhere?

Reveal the explanation

No. A signature demonstrates authorization. Nodes and consensus determine which conflicting spend can belong to the accepted history.

Another route through the ecosystemWhat backs a stablecoin? →