11.10 Help on Active Text and Tooltips

When a region of text is “active,” so that you can select it with the mouse or a key like RET, it often has associated help text. Areas of the mode line are examples. On most window systems, the help text is displayed as a “tooltip” (sometimes known as “balloon help”), when you move the mouse over the active text. See Tooltips. On some systems, it is shown in the echo area. On text-only terminals, Emacs may not be able to follow the mouse and hence will not show the help text on mouse-over.

You can also access text region help info using the keyboard. The command C-h . (display-local-help) displays any help text associated with the text at point, using the echo area. If you want help text to be displayed automatically whenever it is available at point, set the variable help-at-pt-display-when-idle to t.