Chain email is like a game of telephone. It's something that is sent from one person to another, but once it's been sent, each person changes the email a bit and sends it to more people. People usually add something funny or interesting to the email, or forward it on with a message about why it's important. By the time the email has gone to a lot of people, it is usually very different from what it started as. You should be careful because chain emails often contain false information or viruses.