.NET is composed of a CLR and the .NET FCL, and supports multiple languages. The CLR offers several features that free you from the low-level plumbing work required in other environments. The FCL is a large library of code that supports additional technologies such as Windows Presentation Foundation, Windows Communication Foundation, Windows Workflow, ASP.NET, and many more. The FCL also contains much code that you can reuse in your own applications. Through its support of IL, a CTS, and a CLS, many languages target the .NET platform. Therefore, you can write a reusable library with C# code that can be consumed by code written in other programming languages.
Remember that understanding the .NET platform, which includes CLR, FCL, and multiple-language support, has implications in the way you design and write your code. Throughout this book, you'll encounter many instances where the concepts in this chapter lay the foundation of the tasks you need to accomplish. You might want to refer back to this chapter for an occasional refresher.
This chapter has been purposefully as short as possible to cover only the platform issues most essential to building C# applications. If you're like me, you'll be eager to jump into some code. The next chapter does that by introducing you to essential syntax of the C# programming language.