Regardless of what you use .NET components for, you need to be familiar with the essentials of .NET as a component technology and deployment platform. This chapter introduces basic concepts such as the assembly, metadata, and the Common Language Runtime (CLR). You will see how to compose client and class library assemblies and how to consume a binary component in one assembly by a client in another. The chapter then discusses how .NET achieves binary compatibility, demonstrating how .NET supports this important component-oriented principle presented in the previous chapter. Although I use C# to demonstrate the key points in this chapter and elsewhere in this book, the discussion (unless explicitly stated otherwise) is always from a language-agnostic perspective. The information is applicable to every .NET language, so the focus is on the concept, not the syntax. If you are already familiar with .NET essentials both in .NET 1.1 and 2.0, feel free to skip this chapter and move on to Chapter 3.