Definition
A paper wallet traditionally means a printed or handwritten private key together with a receiving address, sometimes represented by QR codes. It is different from writing down the recovery phrase of a modern wallet: that phrase may recover many accounts and keys. In both cases, the paper contains access information, while the assets remain recorded on the blockchain.
How It Works
An address can receive funds without the paper being connected to anything. Spending requires compatible software or hardware to use the private key and create a signature. Importing a key and sweeping its funds are different operations: sweeping normally transfers the balance to a newly controlled address. On UTXO networks, careless partial spending can also mishandle change if the user assumes the original paper covers every resulting output.
Key Considerations
Paper wallets are difficult to create and use safely. A compromised generator, printer memory, photographs or insecure key handling may expose the secret. Paper can be destroyed, fade or be copied without detection. A printed key is not secure merely because it is offline now; its entire creation history matters. Never use a wallet supplied with a private key chosen by someone else, and do not confuse a public QR code with a secret one.