Bitcoin Basics · Episode 3 · 90 seconds, narrated

What is a blockchain?

A short cartoon about the notebook behind bitcoin: pages of payments, each sealed with a code from the page before, kept by tens of thousands of computers. Turn your sound on and press play, or jump to a chapter.

0:00 / 1:32

Numbers in this episode

~10 min: New pages (blocks) are added about every 10 minutes on average; the network adjusts the difficulty to keep that pace.
Jan 3, 2009: The first page, block 0 (the “genesis block”), is timestamped January 3, 2009, 18:15 UTC. It is the only page with no page before it.
970,000+: Pages in bitcoin’s chain on October 10, 2026: the block height was about 970,790 (mempool.space and blockchain.info).
25,800: Publicly reachable computers (nodes) keeping and checking a copy on October 10, 2026, according to btcnodes.io; many more run without being reachable.
4 of 64: The page codes shown are real SHA-256 fingerprints of the pictured pages, cut to 4 characters. Bitcoin’s real block codes are 64 characters long.

Script

Read the narration

For education only; not investment advice. The payments, names and short codes are illustrations. Changing an old page is shown as hard, not impossible: making a change stick means redoing every later page faster than the rest of the network, which the next episode explains. The bitcoin paper calls this a “chain”; the word “blockchain” came into use later. Narration uses a synthetic voice (Kokoro text-to-speech). Part of Bitcoin Basics from The Steady Block: @TheSteadyBlock on YouTube and X, TheSteadyBlock.com.