Authentication Authorization Authentication verifies who you are Authorization verifies what you are authorized to do Authenticating a user on a website means that you verify that this user is a valid user, that is, verifying who the user is using username/password or certificates, etc Authorization is the process of verifying if the user has rights/permission to access certain resources or sections of a website, Example : When u login to access some site then your logon credential (userid/password) identifies Example : After successful logon, you will be granted specific role or privileges to access the site.

Destructor They are special methods that contains clean up code for the object. You can’t call them explicitly in your code as they are called implicitly by GC (Garbage Collector). In C# they have same name as the class name preceded by the "~" sign. Like- class MyClass { public MyClass () { } ~MyClass () { } } Dispose These are just like any other methods in the class and can be called explicitly but they have a special purpose of cleaning up the object. In the dispose method we write clean up code for the object. It is important that we freed up all the unmanaged resources in the dispose method like database connection, files etc. The class implementing dispose method should implement IDisposable which is inherited by interface and it contains GC.SuppressFinalize method for the object it is disposing if the class has destructor because it has already done the work to clean up the object, then it is not necessary for the garbage collector to call the object's Finalize method.