03
Understand custody
A wallet holds access—not coins.
7 articles in this rubric.
Basics · UTXOs and keys
Where Bitcoin exists
Why a balance is a sum of unspent outputs and a wallet holds keys rather than coins.
Read article ↗Practical guideHow to choose a wallet without losing access
Mobile, desktop and hardware wallets: purpose, trade-offs and the rules of reliable backup.
Read article ↗Key loss · 2013 → 20258,000 BTC beneath a landfill
A drive reached a landfill, but the decisive loss came earlier: the only usable copy of access disappeared.
Read article ↗Compromise · June 13, 2011The first major reported theft: 25,000 BTC
A backup existed but could not reverse a transfer after someone gained access to the live wallet.
Read article ↗Research · 2011–2015Why a Phrase from Memory Made a Bad Wallet
The brainwallet experiment: when a convenient human phrase became a predictable private key.
Read article ↗BIP 39 · 2013Twelve Words Are Not a Password
How BIP 39 turns randomness into a readable backup and why people should not invent the words.
Read article ↗Custody · BTC or a product shareThe Fund Holds BTC. What Does the Investor Hold?
Why a bitcoin exchange-traded product can follow Bitcoin’s price without giving its shareholder the same control as a private key.
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