Organic vs. Inorganic Molecules
Molecules can be either organic or inorganic. No, we are not talking about pesticide-free, non-genetically modified, free-range molecules. In chemistry terms, organic means that a molecule has a carbon backbone, with some hydrogens thrown in for good measure. Living creatures are made of various kinds of organic compounds. Inorganic molecules are composed of other elements. They can contain hydrogen or carbon, but if they have both, they are organic. Picky, picky.
You may be wondering why carbon plays such a big role in life. Well, wonder no more! The reason is that carbon has 4 electrons in its outer shell, but, deep down, it really wants 8 electrons instead. With two electrons for every pair, the 8 electrons can form up to 4 single bonds, or some combination of single, double, and triple bonds. Carbon is extremely versatile. If you can act, sing, dance, and play the violin with your toes, you are way more likely to find work than someone who can only do one of those things. Not that being able to play the violin with your toes is an extremely marketable skill or anything...
Think of carbon as the jack-of-all-trades. Carbon's potential to form many kinds and combinations of bonds with many different atoms gives rise to all sorts of molecules of varying shapes and sizes. Living organisms have definitely taken advantage of this ability, which might explain the similarity between the words "organic" and "organism."
Carbon defines organic life on Earth, but some scientists think that silicon could serve a similar function. Check out its placement on the periodic table of elements to see why. Read more here.