Primaries

Will someone please explain:

1. caucuses
2. primaries
3. delegates
4. superdelegates

?

And,

5. Whether my vote matters in TX primaries such that I should pursue an absentee ballot?

Thanks!

EDIT: Ok, ABC explained a bunch of this. And, Facebook wants to know what it will take to get my (under 30) vote--maybe an iPod? YES, YES it will take an iPod. You should give me one. Do it for democracy.