CompTIA A+ Certification

All communications with the kernel are managed by the user mode. It also provides the APIs needed to emulate application and network environments. This enables Windows 2000 to run applications written for Windows 9x, MS-DOS, and POSIX. User mode is comprised of a series of subsystems of which there are two primary groups: integral and environmental. A security subsystem which manages logon requests from users is an example of an integral user mode subsystem. It manages all the rights and permissions granted to user accounts and controls access to resources. The Win32 environment is an example of an environmental user mode subsystem. It functions as an intermediary between legacy Win16 and MS-DOS applications and controls, and Win32-based applications running in a Windows 2000 or Windows XP environment.