What is Public Key?
Crypto Glossary Definition
The address used to send someone an amount of cryptocurrency. If a private key is your password, a public key is your username.
Why Public Key Matters
Your public key (or the wallet address derived from it) is safe to share freely — it's what people use to send you crypto, similar to sharing a bank account number. It cannot be used to move funds out of your wallet.
Public Key in Practice
When a friend wants to send someone 0.05 BTC for splitting a dinner bill, the recipient doesn't need to share anything sensitive to receive it; he simply opens his wallet app, copies the wallet address displayed there, which is derived from his public key, and sends it over text the same casual way he might share a bank account number for a direct deposit. His friend pastes that address into her own wallet, enters the amount, and sends the transaction, which settles on-chain within minutes without either of them exchanging any secret information in the process. He later explains to her, since she's newer to crypto, that this public key is meant to be shared freely and publicly precisely because it can only be used to receive funds, not move them; unlike his private key, which functions like a password and must be guarded closely, the public key functions more like a username or a mailing address, something anyone can know without being able to touch what's actually inside the wallet. Some more privacy-conscious users even generate a fresh receiving address, and effectively a fresh public key, for every transaction rather than reusing the same one repeatedly, since publicly reusing one address can make it easier for outside observers to link someone's transaction history together over time.
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