Definition
A public key is the non-secret member of a cryptographic key pair. In cryptocurrency signature systems, it enables verification without giving the verifier spending authority. A secure construction makes deriving the private key from the public key computationally impractical. Public keys may be represented in different encodings, so their appearance is not identical across networks.
How It Works
A wallet uses a private key to sign transaction data, and validators use the corresponding public information to check the signature. An address is related but not always identical to a public key. Some networks derive addresses by hashing or transforming public keys; other address formats refer to scripts or smart contracts. Always use the receiving format requested by the destination rather than assuming any displayed public key is a valid payment address.
Key Considerations
Publishing a public key does not normally reveal its private key, but public does not mean privacy-neutral. Reusing identifiers can make activity easier to link. Extended public keys used by hierarchical wallets can expose many derived addresses and should not be shared casually. A public key also does not by itself prove a real-world identity: that association needs separate evidence. Never substitute a private key when a service requests public account information.