You may know about a thing called "case sensitive". Some people don't know what it means. You can even see that on Wikia if you make a mistake on your username while logging in. Easter eggs in programs that require writing something, are also case sesnitive.
Let's take "Amy is cute!". If you type "amy is cute!", you will get an error. But if that's not case sensitive, it will be case instensive, which does not require every capital letter to be capital and every small to be small. Let's look on another mistake that everyone can make. Let's again take "Amy is cute!". You can type it like that: "AMy is cute!". See the mistake there?