Object snaps are used to create precise drawings. Use the [F3] key to turn the automatic object snap function on and off. When it’s on, this function automatically “locks” the drawing commands to predefined points (like endpoints and intersections of existing lines).
Type OSNAP at the command prompt to specify the points to which AutoCAD will automatically lock.
Even if the automatic object snap function is off, you can still force AutoCAD to temporarily lock to a specific point in the middle of a drawing command. While drawing, when you’re prompted to specify a point, type the first three letters of the desired snap function (e. g. END for endpoint, MID for midpoint, PER for perpendicular, etc.).
Note: The NODe object snap locks to points. Points are zero-dimensional AutoCAD objects, the appearance of which is controlled using DDPTYPE. Use the DIVIDE command to automatically draw points at a whole number of equally-spaced divisions along a line, circle, or arc; use the MEASURE command to automatically draw points at predetermined equal intervals (e. g. every inch) along a line; lock to these points with the NODe snap.
TRACKING. The object snap tracking function ([F11]) extends the functionality of the basic object snaps. The tracking function “sees” distant points as you’re drawing. When it’s on, and while you’re drawing, move the mouse (without clicking) over a point, and then move the mouse away. The [F3] key must also be “on” in order for [F11] to work.
SCREEN CONTROLS. Related: Instead of clicking [F3], you can click the OSNAP button at the bottom edge of the screen. Instead of clicking [F11], you can click the OTRACK button.