Some types of plaids are the Shepherd's Check, Houndstooth, Glenurquhart Check, Tartan, Windowpane and Tatersall. Gingham is a larger version of Shepherd's Check. Tartan, the pattern that Americans usually mean when they say plaid, has two base colors, or a sett, which forms a third color when the two overlap. For each additional sett added, the colors increase quadratically.
Shepherd's Check is a specific type of tartan with just two colors, typically black and white, that are evenly spaced at six strands of wool so the pattern appears as a series of squares. It was typically worn by shepherds on the English-Scottish border and woven from the wool of their flocks. Houndstooth is also two colors, but is woven with four strands of wool with a warp weave to create a jagged, diagonal pattern.
Glenurquhart Check is also known as glen plaid or Prince of Wales check. Also traditionally woven with black and white, it is a twill of two light and dark stripes crossed over with four light and dark stripes and creates a large pattern of irregular squares and rectangles.
Windowpane plaid is a large, simple check that consists of a base color and another color crossing over it in a series of panes. Tatersall is related to Windowpane creating squares with two colors alternating both vertically and horizontally.