So long as the units of a cryptocurrency have a certain exchange value that can be converted to a central bank currency like the dollar, cryptocurrency can in principle be used as a means of payment. But to actually pay with digital money, the vendor must also accept the cryptocurrency. In order to execute a payment, a pair of keys is required, comprising a public and private key.
The public key is visible to anyone and essentially has the same role as a bank account number: it serves as the sender’s address from which a user carries out a payment with the respective cryptocurrency. Conversely, the private key is used for verifying a transaction, a bit like a password or PIN. It should only be visible to the owner of the crypto address used to sign a transaction. In the case of the latter, this is usually automatically performed by a wallet, the virtual account that stores a cryptocurrency. In other words, users only have to enter the amount and the target address, i.e. the public key, of the payee when making a payment.