The Line Tool is just what it sounds like: a toolbar function in Flash that lets you draw straight lines easily just by pointing and clicking. Just click where you want the line to start, drag, and then release where you want the line to stop.
You can constrain your lines to be strictly vertical or strictly horizontal by holding down the Shift key as you draw them; they will snap to preset angles for perfect right angles or perfect diagonals.
Its one of the important tool and the best to used for animation in flash
