Glossary » keyboard focus
the area or widget on the screen that is currently responsive to keyboard input. The keyboard focus is usually hilited in some way, for instance, with a focus ring around a default button, or the color or details of an active window. The keyboard focus can often be moved solely from the keyboard, often by tabbing between elements in a dialog box.
With respect to windows, the window that currently receives keyboard input is usually the frontmost window, but some systems make whichever window the mouse is in the window that receives keyboard input.