Some of the PNG backgrounds have transparent elements, meaning that their appearance will change depending on what color canvas they are drawn on. Using transparency this way provides the ability to recolor the background on the fly by setting a new canvas color.
If a background does not tile fluidly, it might not be meant to. On the other hand, sometimes there are accidental seams. When in doubt, compare what it looks like with and without tessellation.
Certain adjacent backgrounds may look identical, but if you look closely you will see minor variations through the series.
The works referenced and displayed on this page were authored by kagerato and are presently under copyright. All of the backgrounds shown on, and linked to from, this page are provided at no charge to all individuals, groups, and institutions under each of the following licenses:
As the licensee, your usage should abide by one (and only one) of the licenses. You may not mix and match or otherwise slice and combine different license terms.