Most are free-to-use (ie public domain or copyright-free)means 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 which are still copyright may also be included, if they are particularly relevant.
Most communities have a familiar repertoire of public domain Christmas music, so finding free-to-use hymns for time is simple. The list below doe not include all well known Christmas carols, just ones that are a particularly good fit with the lectionary themes for this feast.
