Encryption can be used to encode email messages so snoopers and hackers can't read them as they are sent across the Internet. Many types of encryption exist, but in the most common one, keys are used. Everyone gets a public and private key. The public key is available for anyone to use to encrypt mail; the private key is used only by the recipient to decrypt it. This illustration shows how to encrypt email with the popular encryption program Pretty Good Privacy (PGP). To start using PGP, someone uses her normal email program to compose a piece of mail. After she composes the mail, she decides whether she wants to encrypt the message.
