By using the background grid, you can more easily create precise drawings in less time. The following Grid options are available from the Settings panel.
Grid - Toggles on and off the visibility of the background grid
Grid Spacing - Specify the size of each grid cell /square
Object Snap > Grid - Toggled on, when you draw, resize, or move an object, it will align or "snap to" the nearest gird lines. Available under Settings > Object Snap. Note - this option is OFF by default.