As C# developers get more experienced, there are a lot of things they pick up along the way that are really useful and important to know, even if they aren't necessarily directly code-related. One of those topics is XML comments, and I've been surprised at how many developers -- even really experienced ones -- don't use them, or even know about them. They're really useful, and they can help you build better software, even if they don't actually change the way your programs behave.