What is "reading comprehension"?

[kaskas106]

And how do I do/get it? I can read fine, I understand words, I follow along with stories (unless they get tediously long ala Fellowship Of The Ring). But I've heard of this thing called reading comprehension, and like... Is it interpreting more than what's being said? And something about themes? Are they also part of it, or something totally different? I interpret all media literally unless told otherwise, so... A lot of this confuses, more than anything, and naked me feel as though I'm doing something wrong.