About Handles and Objects
The system uses objects and handles to regulate access to system resources for two main reasons. First, the use of objects ensures that Microsoft can update system functionality, as long as the original object interface is maintained. When subsequent versions of the system are released, you can use the updated object with little or no additional work.
Secondly, the use of objects enables you to take advantage of Windows security. Each object has its own access-control list (ACL) that specifies the actions a process can perform on the object. The system examines an object's ACL each time an application creates a handle to the object. For more information, see Access Control.