It's called 'show desktop' - it tells you that if you hover your cursor over the tiny vertical bar at the right end of the taskbar.
Taskbar.
True
Desktop
The desktop is the main computer screen that is visible when there are no open windows. It usually has a color, graphic, or photo background with icons for various shortcuts or documents. It is also associated with the taskbar (Windows) and dock (Mac).
[a]Quick launch [b]Systray [c]Taskbar [d]Time
Locking the taskbar refers to a feature in operating systems like Windows that prevents users from accidentally moving or resizing the taskbar. When the taskbar is locked, its position remains fixed, ensuring that icons and shortcuts stay in place. Users can enable or disable this feature through the taskbar's context menu by right-clicking on the taskbar and selecting "Lock the taskbar." This helps maintain a consistent and organized workspace.
It varies depending on your operating system, but in general the bar along the bottom is the taskbar, the picture you see is called the desktop background, and the programs on the desktop background are called icons.
taskbar
The portion of the screen that displays when windows XP is loaded is called the Desktop. It features icons for different programs, the Taskbar and the Start Button.
You right-click on your taskbar and then click on properties. Then you un-select 'Keep the taskbar on top of other windows'.
The main feature of Windows Vista Aero is the way Alt-Tab changed. Instead of small icons it now displays the available tabs in a 3D environment. Another associated feature is the windows popping up when hovering over the tabs in the taskbar.
The taskbar.