A Tartan is made with alternating bands of coloured (pre-dyed) threads woven as both warp and weft at right angles to each other. The weft is woven two over - two under the warp, advancing one thread each pass, forming diagonal lines. The resulting blocks of colour repeat vertically and horizontally in a distinctive pattern of squares and lines known as a sett. Kilts almost always have tartans. Tartan is also known as plaid in North America, but in Scotland this word means a tartan cloth slung over the shoulder or a blanket

In the modern era, specific tartans have become associated with Scottish clans or Scottish (and other) families, or simply institutions who are (or wish to be seen as) associated in some way with a Scottish (or other Celtic) heritage.