A public and private key pair is a pair of asymmetric keys that perform the encrypt/decrypt functions of a secure data transmission, among other things. So, for example:

Robert wants to send Katie a file. Robert would request Katie’s public key to encrypt the file and then encrypt it with her public key. Robert would then send the file to Katie. Katie would then decrypt the file with her private key.

In this way, Katie’s public key is only used to encrypt but can never be used to decrypt, keeping the data safe. And Katie can only decrypt the data with her private key and would never exposes her private key to anyone, keeping her private key safe.

This is the basis for all secure communication. This, however, is also very simplistic language. For a more comprehensive view on asymmetric and symmetric keys and how they are used, a section on how encryption key systems work has been provided.

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