What's an LCD for an iPhone 3G?

I cracks my iPhone and apparently need a digitalizer for the screen even though it still works perfectly. I've heard I need an LCD too, but I have no freaking idea what that is. How much would a screen, digitalizer, and possibly LCD cost together?

Added (1). Thanks for the answer, but obviously I have a higher education than you since I'm able to use proper punctuation. And to answer your question, no, I'm not dumb; I'm just looking for an honest answer, ***.

Are you dumb? It means the screen that lights up u tard. Don't get an iphone. Get an education

It depends really, I looked into it with Apple and they said $150 when I had my 3G (I have a 4 now). I wasn't gonna pay that much, so I went to iscreensfix.com and followed their guide and videos on how to replace it. I found it extremely easy and it was pretty quick too, take a look at their site. Overall it cost me no more than $40