Reflection enables you to find out information about types in your assemblies during run time. Using reflection, you can find out the details of an object's methods in terms of its access modifier ( private, public etc.), you can discover the name and types of parameters in a methods signature.
If you have used the class browser , then you can get an idea of the sort of information one can retrieve using reflection.
The System.Reflection namespace contains many classes and methods that provide you with the functionality just described above.