Processor Mode - the various ways in which the processor creates an operating environment for itself. (See my other article for details under Hardware section)

Dynamic Link Library - an executable file that acts as a shared library of functions. (for this too I have an article published in the forums)

Graphics Device Interface - provides functions and related structures that an application can use to generate graphical output for displays, printers, and other devices. Windows provides GDI for all graphics output by applications and then maps it to intended devices using drives.

Object Linking & Embedding - compound documents containing embedded objects or linked objects that retain the native data used to create them (or a link to that data) as well as information about the format. Like you can insert a Excel Sheet in a Word document.

Virtual Memory - a method of extending the available physical memory on a computer.

File System - the overall structure in which files are named, stored, and organized.

Message Queue - system passes input and control information to a window procedure in the form of messages. Messages are generated by both the system and applications. These messages are maintained in the form of a queue. It's the method by which Windows informs applications what input has been given by the user and the system.

Device Independence - applications can draw and print output on a variety of devices. Applications print to Device Contexts provided by GDI Layer & the rest is handled by GDI Layer.

Component Object Model - is a platform independent, object oriented system for creating binary software components that can interact. It is the foundation technology for Object Linking & Embedding (compound documents) and ActiveX (Internet enabled components) technologies, as well as others.

Distributed Component Object Model - extends the component object model to support communication among objects on different computers - on LAN, WAN, or even the Internet.

Well what about the GUI (Graphical User Interface) and some of those. You might have forgotten a few.