I am very confused: I have been browsing through the Internet, searched some blogs etc, but I'm really getting confused. My question is about a `Caesar cipher` and a `simple substitution cipher` -- is there any difference? Some blogs when I search `simple substitution cipher` I get `Caesar cipher`. Is there anyone who can explain to me if they are the same or not? I really want to make a program that will work as a `simple substitution cipher`.