First steps

1. 1
   Easy levelThe Life of a Transaction

   Follow one payment through all six stations, from the wallet to a block buried under confirmations.

   Open the model I've tried it

   Optional challenge You pay 120,000 sat using a 137,250 sat coin, and the fee is 1,692 sat. How much comes back to you as change?

   15,558 sat 17,250 sat 137,250 sat Check answer

2. 2
   Easy levelThe UTXO Machine

   See that bitcoin is held as separate pieces, and that spending a piece always spends all of it.

   Open the model I've tried it

   Optional challenge What happens to a coin (a UTXO) when you only need part of it?

   It is split on the blockchain and the rest stays where it was It is spent completely, and the rest comes back to you as a new change output The network keeps the rest as a fee Check answer

3. 3
   Easy levelThe Chain of Blocks

   Change something in an old block and watch every block after it break.

   Open the model I've tried it

   Optional challenge Why does changing an old block break all the blocks after it?

   Each block contains the fingerprint (hash) of the block before it Blocks are stored on one central server Old blocks are locked with a password Check answer

4. 4
   Easy levelThe Global Bitcoin Network

   Send a transaction into the network and watch thousands of independent computers pass it on.

   Open the model I've tried it

   Optional challenge Who checks a new transaction before it spreads?

   A central Bitcoin server Every node checks it for itself before passing it on Only the miners Check answer

5. 5
   Easy levelThe Bitcoin Halving Clock

   Turn the clock and see why new bitcoin arrives more and more slowly.

   Open the model I've tried it

   Optional challenge From block 840,000 (April 2024), how much new bitcoin does each block create?

   6.25 BTC 3.125 BTC 50 BTC Check answer

Finished? Choose another path or explore freely.