So far in this book you have worked without using a visible grid on your canvas. With the aid of the Smart Alignment Guides and the Smart Distance Guides, you have made perfectly aligned and good-looking diagrams. If your diagrams are much like the ones you have created so far, you may never have to use a grid when placing shapes.
However, if you are making diagrams, which represent "real life objects" – using a grid is a must. These kinds of diagrams can be anything from a diagram showing the new office layout – to a diagram for showing office visitors where various parts of the building are.
You turn the visibility of grid lines on or off by using the View | Gridlines menu command. You could also use the ⌘+\ keyboard shortcut command.
In the previous screenshot, you see the canvas with grid lines. The thick grid lines are called the Major Gridlines, while the thinner lines are called the Minor Steps.