In AutoCAD, the function keys (except for F1 and F12) act as switches or toggles. Of all the function keys, F3 (object snap) and F8 (“ortho”) tend to be the most frequently used. The others tend to be used comparatively rarely.
F1 brings up AutoCAD’s Help.
F2 opens and closes the Text window, which is simply an expanded version of the command window. It provides no additional functionality other than the ability to look back at what you just typed.
F3 turns the object snap function on and off.
F4 turns a peripheral drawing tablet (if connected) on and off.
F5 cycles between isometric planes. This function is used for creating isometric drawings. (To experiment with this, type SNAP, change the Style to Isometric, and draw some lines. Use F5 to cycle between planes.) Also see F9.
F6 cycles between coordinate displays, at the bottom left-hand corner of the screen.
F7 turns the drawing grid on and off. To specify the gird extents, type LIMITS. To specify the grid spacing, type GRID.
F8 turns the orthographic lock function on and off.
F9 turns the automatic snap function on and off. When on, AutoCAD snaps to an invisible rectangular or isometric grid, not necessarily the same grid as specified using the GRID command. To specify the snap settings, type SNAP.
F10 turns polar tracking on and off. It also automatically turns F8 (ortho) off. Polar tracking displays angles and distances while drawing.
F11 turns the automatic object snap tracking function on and off.
F12 has no function.