What is SHA-256?
SHA-256 is a cryptographic hash function from the SHA-2 family. It produces a 256-bit output from any input. Bitcoin uses double-SHA-256 to hash block headers, transactions and Merkle trees.
Why SHA-256 matters
Understanding SHA-256 is part of building a solid mental model of how Bitcoin, blockchain and Web3 systems actually work. Concepts in the Cryptography 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 SHA-256 through hands-on, browser-based simulations. Build the mental model by actually using it:
- Bitcoin 101 — interactive fundamentals course
- Bitcoin Proof of Work — mining, hashing and consensus
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Related terms
- Hash Function — A deterministic function mapping arbitrary input to fixed-size output.
- Merkle Root — The single hash summarising all transactions in a block.
- Block Header — The metadata at the top of each block.
More cryptography terms
- Digital Signature — A cryptographic proof that the holder of a private key authorised a message.
- ECDSA — Elliptic Curve Digital Signature Algorithm.
- Merkle Tree — A binary tree of hashes used to summarise data efficiently.
- Private Key — The secret number that authorises spending from an address.
- Public Key — The shareable counterpart to a private key.
- Zero-Knowledge Proof — Proving you know something without revealing what it is.
- Schnorr Signature — A signature scheme enabling key aggregation.
- Merkle Proof — Compact proof that a transaction is in a block.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.