TartanA tartan isn't synonymous with plaid. The tartan of a Celtic clan is a sequence of colors and shades unique to the plaid material authorized for use by members of that clan for ceremonial kilts, ties, and whatnot. More simply stated, every clan, which is not just each family, has a separate tartan. There are forms of Scottish heraldry.
In modern times, tradition has allowed members of the British Royal Family the use of the Royal Stewart tartan, regardless of whether they are affiliated by blood to the Stewart clan.
(This article is a stub.)