As a writer of fantasy, it's common for castles and forts to make an appearance in my pages. So, to be able to obey the old saying "Write What You Know," it was necessary to acquaint myself with the ways of castles and all the terminology involved. But because I don't frequent actual castles often enough (those tickets to Europe are rather expensive), I do still get confused on all the "buttresses" and "baileys" and "barbicans." The terms that tend to give me the most trouble, oddly enough, are the ones I use most frequently. Either my resources are giving me conflicting information or my brain habitually remembers things backwards (which I tend to think is the case).
To keep things straight, I've provided a diagram. Our model is Penrhyn Castle in Bangor, Wales. So the next time you tour your castle and watch for baddies approaching on the horizon, you will know which part you are ducking behind and which part to shoot your arrow through: