public key
A cryptographic key mathematically derived from your private key. It can be shared publicly and is used to generate your Bitcoin address and verify transaction signatures.
The public key is generated from the private key using elliptic curve cryptography, specifically the secp256k1 curve. This is a one-way operation: you can derive the public key from the private key, but it is mathematically infeasible to reverse the process.
Your Bitcoin address is a compressed and hashed version of your public key. When someone sends Bitcoin to your address, they are locking funds that only your private key can unlock.
When you spend Bitcoin, your wallet broadcasts your public key along with a digital signature. Anyone on the network can use your public key to verify that the signature is valid, confirming the transaction was authorized by the private key holder, without ever learning the private key itself.