Thomas Sutton, 1861. First colour photograph — of a tartan ribbon, demonstrating James Clerk Maxwell's three-colour theory.
Tartan, also known, especially in American English, as plaid, is a patterned cloth consisting of crossing horizontal and vertical bands in multiple colours, forming repeating symmetrical patterns known as setts. Tartan patterns vary in complexity, from simple two-colour designs to intricate motifs with over twenty hues. Originating in woven wool, tartan is most strongly associated with Scotland, where it has been used for centuries in traditional clothing such as the kilt. Specific tartans are linked to Scottish clans, families, or regions, with patterns and colours derived historically from local natural dyes. Tartans also serve institutional roles, including military uniforms and organisational branding.