Jigsaw Download, or short jigdo, is a tool designed to ease the
distribution of very large files over the internet, for example CD or
DVD images. Its aim is to make downloading the images as easy for
users as a click on a direct download link in a browser, while
avoiding all the problems that server administrators have with hosting
such large files. It accomplishes this by using the separate pieces
of any big file (such as the files contained within a CD/DVD image) to
create a special "template" file which makes reassembly of the big
file very easy for users who only have the pieces.