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The Bitcoin School
For people who want to understand Bitcoin. Not flip it.
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Start the JourneyLooking for one thing? The glossary explains 505 Bitcoin terms in plain language.
Plain language. Sourced chapters. Live on-chain data from a real node. Huge glossary, Rabbit Holes, and one opinionated Journey from "what is money?" to running a full node. No altcoins, no affiliate links, and no signup needed to read any of it.
From the glossary
Government-issued money, like USD or EUR, unbacked by any physical commodity and relying on state authority for value.
Read full entryNew on the site.
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Rabbit Hole · 21 min
Brain Wallets: Why a Passphrase You Made Up Is a Key Someone Can Guess
A brain wallet turns a phrase you made up into a Bitcoin private key, and since at least 2013 programs have guessed such phrases and emptied the wallets. In February 2014 James D'Angelo funded three of them on video. The chain shows what happened to his coins and to the famous phrases, and the best-known site closed in 2015.
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Rabbit Hole · 16 min
The Time Warp: How Lying About the Time Could Break Bitcoin's Difficulty
A seam in Bitcoin's 2009 code would let a miner with most of the hash rate drive difficulty to its minimum within weeks, in under six with all of it. It has been used on other coins and planted once on testnet, never used on Bitcoin, and the fix is written and waiting for a soft fork.
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Rabbit Hole · 14 min
Quindecillions: Why Nobody Can Stumble on Your Bitcoin
After a vanity address search, readers ask whether the address already had coins in it and how many wallets the search found on the way. Every Bitcoin address is a drawer. There are about 1.5 x 10^48 of them, 57 million hold coins, and no search on record has landed on a funded one by chance. The same arithmetic is why nobody has to register a key before using it.
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All rabbit holesCustody and Privacy
How do I hold it safely and privately?
- Mt. Gox to FTX: The Custody Graveyard
- Privacy on Bitcoin: What Works and What Doesn't
- Use It Once: Why Reusing a Bitcoin Address Is Dangerous
Hard Questions
The strongest objections, including where the critics are right.
- Quantum and Bitcoin
- Bitcoin and Energy
- Rat Poison, Tulips and a Pet Rock: Everything Bitcoin's Been Called (so far)
Corrected in public.
All corrections-
The Time Warp: How Lying About the Time Could Break Bitcoin's Difficulty
Satoshi's announcement, "Bitcoin v0.1 released", reached the Cryptography Mailing List on 8 January 2009 (14:27 EST, 19:27 UTC). The chapter and its Spanish edition now say the 8th, and the announcement is listed in the sources.
What was wrong -
The transaction had two outputs of 92,233,720,368.54275808 BTC each, which add up to 184,467,440,737.08551616 BTC. That is one million satoshis short of 2^64, which is why the total wrapped around to minus 0.01 BTC. The chapter now gives that figure and says half went to each address.
What was wrong -
Rat Poison, Tulips and a Pet Rock: Everything Bitcoin's Been Called (so far)
January 2025 is when the Legislative Assembly passed the reform (Decreto Legislativo No. 199, 29 January 2025, published in the Diario Oficial the next day). Its Article 8 puts it in force ninety days after publication, at the end of April 2025. The chapter and the text description of its bans diagram now say so, and the decree is listed in the sources.
What was wrong