Object SNAP modes
The object SNAP mode is a SNAP mode where the mouse cursor is locked to commonly needed points, or we can say characteristic points, on entities (such as their end-points, middle points, centres of circles, etc.).
If required, the object SNAP mode can be combined with the grid SNAP mode.
A required kind of the object SNAP mode can be selected (activated) in the Cursor snap setting dialogue.
The picture above shows "in action" the SNAP mode set to Midpoints.