Backlighting is something you see in movies and magazines but not often in scrapbooks or Christmas cards. It's not a technique you'll use very often but when it's a good idea, it's a GREAT opportunity!
Backlighting is just what it sounds like--light behind a subject making the subject appear totally black, a silhouette. Think about a winter scene. There's a hill with one, lone tree on top. There are no leaves on the tree but the look is just amazing. You love the way it looks. Unfortunately, the sun is off to the side and there's a shadow that just doesn't look great.
In some cases there's nothing you can do, but if you're really lucky, you can move around the hill so the sun is behind the hill but is lighting the tree so it's totally silhouetted against a light sky. Amazing!
This works just as well when you have a sunset shot and there is one lone person standing on the beach facing that sunset. It gives the shop perspective and a sense of drama.
This kind of photo isn't going to happen very often but if you look for those opportunities, you may just get something you'll be proud to display on your walls. This is the stuff that makes your co-workers go, "ooh, that's amazing."
Of course you can't always get around the hill and there may not be a lone person that just happens to be standing on the beach when you need one. That's fine, too. The photo will be just fine without that backlit subject but keep your eyes open. There's really nothing quite like hearing, "Wow" when we show off our photos, is there?