What is Double Spend?
A double-spend attack tries to convince different parties that the same unit of cryptocurrency has been sent to each of them. Blockchain consensus prevents this by ordering transactions in blocks and rejecting any later transaction that conflicts with a confirmed one.
Why Double Spend matters
Understanding Double Spend is part of building a solid mental model of how Bitcoin, blockchain and Web3 systems actually work. Concepts in the Bitcoin category sit at the foundation of the broader stack — get them right and the rest is far easier.
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Reading the definition is a start. ZeroToBlock teaches concepts like Double Spend through hands-on, browser-based simulations. Build the mental model by actually using it:
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Related terms
- UTXO (Unspent Transaction Output) — Bitcoin's accounting model: balances as a set of unspent outputs.
- Confirmation — A block built on top of the block containing a transaction.
More bitcoin terms
- Address (Bitcoin / Crypto Address) — A public destination for receiving cryptocurrency.
- Block Header — The metadata at the top of each block.
- Block Reward — New coins paid to the miner of a block.
- Difficulty — A parameter that controls how hard it is to mine a block.
- Halving — The scheduled 50% cut in Bitcoin's block subsidy.
- Hash Rate — The total computational power securing the network.
- Mining — Producing new blocks by performing Proof of Work.
- Nakamoto Consensus — Bitcoin's consensus rule: follow the chain with the most work.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.