Most are free-to-use (ie public domain or copyright-free) meaning the words can be copied and sung to at least one tune with no concerns about copyright or performance licensing. Many such hymns are old/traditional - but where possible a variety of styles / genres are included.
A small selection of hymns that are still be copyright may also included where they are particularly fitting.
Suggestions about other free-to-use hymns that could be included are welcome; please leave a message in the Comment box near the bottom of the page.