A tricolour (three colours) is a flag or banner more or less equally divided (horizontally, vertically, or, less frequently, diagonally) into three bands of differing colours. The term is somewhat misleading, as many tricolours have more than three colours, as they are often charged with contrasting emblems (the flag of India as a prominent example).

Besides carrying an emblem, another means by which a tricolour may have more than three colours is through the use of fimbriation: the separation of colours on a flag by a narrow contrasting stripe. In a fimbriated tricolour, the three broad bands are separated by two thin stripes on either side of the central band. Flags of this type include the flags of the Gambia, Kenya, Namibia, Tanzania, and Uzbekistan.

The tricolour is a specific type of triband. In a triband, the design is of three vertical, horizontal, or diagonal stripes, often formed—from a heraldic point of view—by the placement of a vertical or horizontal stripe (a pale or a fess, respectively), over a background. The triband may thus have two stripes of the same colour split by a stripe of a second colour (examples of this include the flags of Argentina, Austria, Barbados, Belize, Cambodia, Canada, Colorado, El Salvador, French Polynesia, Georgia (U.S. state), Guatemala, Honduras, Laos, Latvia, Lebanon, Mongolia, Nicaragua, Nigeria, Norfolk Island, Peru, and Spain).