A paper wallet is a printed piece of paper with information about a public key and private key pair that can be used for crypto transactions and stored securely offline. A paper wallet is a non-custodial, cold storage wallet as it gives you complete control over the keys used to access your cryptos and is stored offline.
A Bitcoin paper wallet, for instance, would contain the public and private keys needed to approve transactions on the Bitcoin network. The paper wallet would consist of two strings of characters for each key and QR codes that contain this information and can be accessed quickly.
Paper wallets were among the most popular ways to store large crypto holdings securely and disconnected from the internet. However, with innovation in non-custodial, cold storage wallets, the paper wallet has become more cumbersome for securely storing Bitcoin and other cryptos.