CoinucationPublic Key
A public key is derived from a private key and can be shared freely; it is used to verify signatures and to generate receiving addresses.
A public key is mathematically derived from a private key using elliptic curve cryptography. The derivation is one-way: it is easy to compute the public key from the private key but infeasible to go backward. This asymmetry is what lets you prove ownership without revealing the secret.
When you sign a transaction with your private key, anyone can use your public key to confirm the signature is valid. The network does this for every transaction. Addresses are shortened, hashed forms of public keys, which is why you share an address rather than the full key to receive funds.
Bitcoin and Ethereum both use the secp256k1 curve, so the keys look similar in structure, but address formats differ. Solana and several newer chains use a different curve called Ed25519. In all cases the public key or address is safe to publish, while the private key must stay secret.
What is a private key? covers this in 6 minutes, with a quiz at the end.