Illustrator comes with many patterns that you can access in the Swatches panel and in the Illustrator Extras folder on the Illustrator CD. You can customize existing patterns and design patterns from scratch with any of the Illustrator tools. Patterns intended for filling objects (fill patterns) differ in design and tiling from patterns intended to be applied to a path with the Brushes panel (brush patterns). For best results, use fill patterns to fill objects and brush patterns to outline objects.

When designing patterns, it helps to understand how Adobe Illustrator tiles patterns:

• All patterns tile from left to right from the ruler origin (by default, the bottom left of the artboard) to the opposite side of the artwork. To adjust where all patterns in your artwork begin tiling, you can change the file’s ruler origin.

• Fill patterns typically have only one tile.

• Brush patterns can consist of up to five tiles—for the sides, outer corners, inner corners, and the beginning and end of the path. The additional corner tiles enable brush patterns to flow smoothly at corners.

• Fill patterns tile perpendicular to the x axis.

• Brush patterns tile perpendicular to the path (with the top of the pattern tile always facing outward). Also, corner tiles rotate 90° clockwise each time the path changes direction.

• Fill patterns tile only the artwork within the pattern bounding box—an unfilled and unstroked (non-printing) rectangle backmost in the artwork. For fill patterns, the bounding box acts as a mask.

• Brush patterns tile artwork within the pattern bounding box and protruding from or grouped with it.