Dragging a master shape from a stencil onto a page is the fastest way to create a Visio drawing. As the name implies, dragging means that you point to a shape with the pointer tool, hold down the left mouse button, and then move the mouse, dragging the shape with it. Release the mouse button and the shape drops. You might notice that as you drag, Visio snaps the shape to the nearest grid line. This snapping is the subtle tug that you feel as you drag the shape and is a key method you’ll use to align shapes within diagrams. The grid line that the shape snaps to is one of the faint lines that look like graph paper lines on the page. Visio 2007 displays these lines by default.
Visio 2007 also can snap shapes to other objects, and you can control how much “tug” the snapping exerts. You can turn snapping off. For details, see the section titled “Snapping Shapes for Automatic Alignment” in Chapter 16, “Measuring and Dimensioning with Precision.”