Original lithographs are generally regarded as somewhere between an original work and a signed limited edition print.
Each one is produced by hand; a plate is etched and inked, paper then pressed onto the plate.
The edition is relatively small, in this case 75, as a result, they are rare and sought after items. Trending towards minimalism and black/white images, due to the mentioned printing process, there are no two exactly the same.
This technique has been used for over two hundred years to create pieces.