What is Private Key?
A private key is a large random number known only to the owner. It is used to produce digital signatures that authorise transactions. Whoever knows the private key controls the funds — protect it accordingly.
Why Private Key matters
Understanding Private Key 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.
Learn this interactively
Reading the definition is a start. ZeroToBlock teaches concepts like Private Key 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
- Public Key — The shareable counterpart to a private key.
- Digital Signature — A cryptographic proof that the holder of a private key authorised a message.
- Wallet — Software or hardware that manages your private keys.
- Seed Phrase — A human-readable backup of a wallet's private keys.
More cryptography terms
- ECDSA — Elliptic Curve Digital Signature Algorithm.
- Hash Function — A deterministic function mapping arbitrary input to fixed-size output.
- Merkle Root — The single hash summarising all transactions in a block.
- Merkle Tree — A binary tree of hashes used to summarise data efficiently.
- SHA-256 — The hash function Bitcoin uses everywhere.
- 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.