This chapter presents three aspects of .NET security. First, it provides a broad overview of major .NET security features. This review exposes you to important concepts and illustrates how the elements of .NET security differ from one another. Second, you learn how to perform secure data access and data manipulation by using ADO.NET and Access user -level security together in Windows applications. The third aspect of .NET security examined in this chapter focuses on Web applications. In a step-by-step fashion, you learn how to use forms authentication to secure the Web forms at a Web site with an Access database.