The second concept was the wider acceptance of the granting of charters by the Crown and other powerful land owners to the chiefs, chieftains and lairds which defined the estate settled by their clan.
This was known as their oighreachd and gave a different emphasis to the clan chief's authority in that it gave the authority to the chiefs and leading gentry as landed proprietors, who owned the land in their own right, rather than just as trustees for the clan.
Many clans have their own clan chief; those that do not are known as armigerous clans.
Clans generally identify with geographical areas originally controlled by their founders, sometimes with an ancestral castle and clan gatherings, which form a regular part of the social scene.
However, in some cases the direct heir was set aside for a more politically accomplished or belligerent relative.
There were not many disputes over succession after the 16th century and, by the 17th century, the setting aside of the male heir was a rarity.
Under Scots law, the chief is recognised as the head of the clan and serves as the lawful representative of the clan community.
Today, anyone who has the chief's surname is automatically considered to be a member of the chief's clan.
Also, anyone who offers allegiance to a chief becomes a member of the chief's clan, unless the chief decides not to accept that person's allegiance.
Most clans have their own tartan patterns, usually dating from the 19th century, which members may incorporate into kilts or other clothing.
The modern image of clans, each with their own tartan and specific land, was promulgated by the Scottish author Sir Walter Scott after influence by others.