Object snaps are a handy visual tool to help you identify precise locations on objects. With object snaps turned on, anytime your cursor moves over an object in the drawing, a highlighted shape will appear to indicate a snap location. If you pick a point on the screen while an object snap is highlighted, your cursor will snap to the selected object snap. You can greatly increase your drafting speed if you learn how to take full advantage of object snaps to help avoid selecting incorrect points in the drawing.
You can select which object snaps will be available while you are drafting by setting up the Osnap Settings window. You can access this window by typing in "osnap" in the command line or by selecting the Osnap Settings menu item from the object snap context menu. See above on how to access the object snap context menu. With the Object Snap window displayed, select the checkbox next to each object snap you would like to turn on. Alternately, you can type in "sn" in the command line to automatically turn on the Endpoint, Midpoint, Center, Intersection, and Perpendicular snaps.
You can toggle objects snaps on and off by selecting the object snaps toolbar button located on the toolbar below the command line. This can be useful when you are drafting and in an area crowded by other entities, and the cursor is snapping to objects that you do not wish to snap too. Using the toolbar button will turn off all snaps until you toggle the snaps on again. If you wish only to turn off snaps for a single selection, then use the None snap override.
Often you will want to snap to a specific object snap, but many different snap points may be available. To quickly select a specific snap point, you can use the Snap Override feature. Holding down the Shift key and right-clicking the mouse in the drawing will display the Snap Override context menu. Selecting any object snap from this menu will turn off all other snaps and only display the selected snap in the drawing. As soon as you pick a point in the drawing, the default object snaps will turn back on.
Object Snap can also be accessed from the button near the bottom of the screen. Entering the command "sn" will automatically turn on commonly used snaps.