What is private key?

When dealing with cryptocurrency, a user is usually given a public address and a private key to send and receive coins or tokens. The public address is where the funds are deposited and received. But even though a user has tokens deposited into their address, they won’t be able to withdraw them without the unique private key. The private key can take a few different forms, usually depicted as a series of alphanumeric characters, which makes it hard for a hacker to crack. Most users represent their wallet keys in wallet import format, which has 51 characters. Think of a public address as a mailbox, and the private key as the key to the box. On any wallet, by importing the private key and setting a new password you can import the assets from the previous A wallet into the B wallet. For example, if a mobile phone is lost, the assets can be recovered by simply importing the private key.