Topic summary
Windows Executive

Extracted from the Wikipedia article Architecture of Windows NT.
Executive
The Windows Executive services make up the low-level kernel-mode portion, and are contained in the file ntoskrnl.exe. It deals with I/O, object management, security and process management. These are divided into several subsystems, among which are Cache Manager, Configuration Manager, I/O Manager, Local Procedure Call (LPC), Memory Manager, Object Manager, Process Structure and Security Reference Monitor (SRM). Grouped together, the components can be called Executive services (internal name Ex). System Services (internal name Nt), i.e., system calls, are implemented at this level, too, except very few that call directly into the kernel layer for better performance.