Now that we have reviewed much of what we know about nouns, it is time to learn what cases are.

We actually have already seen cases in action. Let's use the pronoun as an example. Would you say,

"Me wants to visit her"?

Of course not. Why?

You could answer, "That sounds weird." But why does it sounds weird? Why is it wrong?

You could answer, "Because we say, 'I want to visit her.'" But again, let me ask the question, Why? Why do you use "I" and not "me"?

To learn the answer, we need to learn what a "subject" is.