What are the basic parts of the Windows 10 graphical user interface (GUI)?

Here are a few selected terms from Microsft’s MSDN website called Glossary of UI Terminology.

desktop The visual work area that fills the screen. The desktop is also a container and can be used as a convenient location to place objects stored in the file system.

menu button A command button that displays a menu.
menu command A choice on a menu.
taskbar A special toolbar that docks on an edge of the desktop supplied by the system. The taskbar includes the Start button, a button for each open primary window, and a status area.
The system tray is located in the Windows Taskbar, usually at the bottom right corner next to the clock. It contains miniature icons for easy access to system functions such as antivirus settings, printer, modem, sound volume, battery status, and more.