Encryption is used to scramble information so that it can be sent safely without anyone else being able to read it. The information is encrypted with a password or key that is needed to read the information again. If you visit a website on the internet that starts with 'https://' then this means that all of the information you are looking at or sending is being securely encrypted. One of the oldest methods of encryption is the caesar cipher. This works by shifting each letter of the message forward a specific number of paces in the alphabet. To read the message you need to know how many places each letter was moved (this is called the key).
Can be used as an introduction to data encryption. A task could be set where students attempt to encrypt and send messages to each other. Other students attempt to break that encryption by working out the encryption key and pattern - have the letters been shifted or substituted?