Security Syntax
Code that targets the common language runtime can interact with the security system by requesting permissions, demanding that callers have specified permissions, and overriding certain security settings (given enough privileges). You use two different forms of syntax to programmatically interact with the .NET Framework security system: declarative syntax and imperative syntax. Some operations can be done using both forms of syntax while other operations can be performed using only declarative syntax. You should be familiar with both forms.
See Also
Concepts
Declarative Security
Imperative Security
Code Access Security Basics