Caesar Shift Cipher

Today I wanted to teach you about the Caesar Cipher, otherwise known as a Shift Cipher which is pretty easy to understand seeing that all you need to know to encode or decode it is the shift value, which let's say is 13.

So encrypting the message: "a piece of cake" looks like this: n cvrpr bs pnxr. And then to get the message back you rot the first letter of the alphabet with another letter of the alphabet 13 times and that's why it's called a ROT13 Algorithm.