The Grid guide acts as a customizable graph paper where the basic unit is the pixel.
The use of a Grid can be very useful to draw parallel line, a square with round corners, align a text on a vertical line...
The Grid guide is a little bit different from the previously seen guides. Indeed, as soon as you create one, a virtual Grid appears.
You then have access to all of its options in the Guidelines panel.
As for the other guides, the first options (Eye, Snap, Transparency) have the same utility and parameters.
The X coord and Y coord allow you to change the position of your Grid guide. They will help to shift the grid on the plane defined by the working area. These values can be negatives. It is possible to change these parameters with the mini-elevators on the right or with the numeric fields.
The Width and Height values can be used to modify the width and height of the squares of the Grid. It is also possible to change these parameters with the mini-elevators on the right or with the numeric fields.
The Edit function is not active for the Grid guide, you need to use the panel's parameters.
The Assist function is not active for the Grid guide, you need to keep the Snap active to draw lines following the grid's squares.
You obviously can add as many Grid guides as you wish, and they can be combined to other guides.
Here, the Grid guide has helped to create a perfect Ellipse grid.