Public key
A public key is the other half of a key pair, derived from the private one. An address for receiving funds comes from it, and it can be shared freely: the private key cannot be computed back from it.
How it works
A private key becomes a public one through an operation that is easy in one direction and infeasible to reverse. The public key is then hashed to produce an address, the string you hand out for a transfer.
Signing a transaction uses the private key; the network verifies the signature with the public one. That confirms the instruction came from the address owner without the network ever learning the secret.
So an address is safe to publish anywhere: a website, a chat, a business card. The only thing it exposes is its transaction history, because the blockchain is public.
What to know
- An address is not the public keyAn address is derived from the public key by hashing. In most situations what you handle is the address.
- A fresh address per paymentWallets generate new addresses from a single seed phrase. That is about privacy rather than security: linking payments becomes harder.
- The history is publicGive an address once and you show the recipient its entire balance and every transaction on it.
- The network mattersEthereum and BNB Chain addresses look identical but the networks differ. A matching format does not mean compatibility.