Tartan is a pattern consisting of criss-crossed horizontal and vertical bands in multiple colours. Tartans originated in woven wool, but now they are made in many other materials. Tartan is particularly associated with Scotland. Scottish kilts almost always have tartan patterns. Tartan is often called plaid in North America, but in Scotland, a plaid is a tartan cloth slung over the shoulder as a kilt accessory, or in reality a plain ordinary blanket such as one would have on a bed.
Source : Wikipedia