What is Blockchain?
A blockchain is a data structure of blocks linked by cryptographic hashes, replicated across many independent nodes and updated by consensus. The structure is append-only: changing any past block would invalidate every later block's hash.
Why Blockchain matters
Understanding Blockchain is part of building a solid mental model of how Bitcoin, blockchain and Web3 systems actually work. Concepts in the Blockchain category sit at the foundation of the broader stack — get them right and the rest is far easier.
Learn this interactively
Reading the definition is a start. ZeroToBlock teaches concepts like Blockchain 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
- Browse all interactive blockchain courses
Related terms
- Block — A bundle of transactions added to the blockchain.
- Hash Function — A deterministic function mapping arbitrary input to fixed-size output.
- Consensus Mechanism — The rules a network uses to agree on the canonical chain.
More blockchain terms
- Fork — A divergence in the blockchain or its rules.
- Node — A computer participating in the blockchain network.
- Proof of Stake — A consensus mechanism where validators stake capital instead of burning energy.
- Reorganization (Reorg) — Replacing recent blocks with a competing chain that has more work.
- Transaction — A signed instruction that updates the blockchain state.
- Block Time — Average interval between consecutive blocks.
- Genesis Block — The first block in a blockchain.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.