Clan: "A clan is a group of people united by
kinship and descent, which is defined by perceived descent from a
common ancestor, group or family collective. Kinship bonds are the
basis of loyalty and common support between clan members, and is
expressed in shared traditions, symbols, and marks of the clan
inheritance and unity.
The clans originate from powerful families in ancient times and the
clan system was the basic system of social power and organisation in
all of the ancient peoples who came to, and remain part of,
Scotland." (http://www.clans.org.uk/clans.html).
Many clans and surname groups have Web sites. The list below is by no means exhaustive, but it's a start. Some clans have genealogists, and some families have done a lot of ancestry research that can help you in your quest.
If you know of a clan or surname Web site that should be added, please use the Contact Us link to let us know!