Caesar cipher is a very simple encryption method and is easily cracked if one studies the frequency of repeating letters. To improve the strength of the encryption method a more complex key could ...

One way is to encrypt the message—that is, use a secret code that only you and your friend know. Try this activity to learn how to create your own “Caesar cipher,” a popular type of code ...

It's easy to decrypt if you take some time to figure it out, but it's plenty to keep non-motivated people from spying on your stuff. This is just one useful personal encryption method of many.