The triband is one of the most common designs of flag, and is the design of some 30% of all current national flags.
As the name suggests, the main feature of the design of a triband is three parallel bands of colour. If the three bands have three different colors, the triband is a tricolour.
In its simplest form, the triband consists of three equally sized horizontal or vertical stripes and nothing else. Examples of horizontal tribands include the national flags of Austria and Germany, and examples of vertical tribands include the national flags of Nigeria and France. In each of these pairs, the second named flag is also a tricolour.
Diagonal tribands are less common, and often do not have stripes of equal areas or widths. An example is the flag of the Republic of the Congo. Such flags are often not considered tribands by vexillologists, but rather are described as having a single diagonal stripe (heraldically, a bend) on a one- or two-coloured background (or field).
More complex tribands include flags charged or defaced with an emblem (such as the national flag of Croatia) or flags with bands of unequal size (such as the national flag of Colombia). The most famous complex triband is arguably the national flag of Canada, which is charged with a maple leaf and has bands of uneven size. The ratio of the bands on this latter flag (1:2:1) has led to the term Canadian pale to refer to any central vertical band on a triband which is twice the size of the bands on either side.
Some tribands, such as the flag of the Gambia, are fimbriated. This means that between the stripes there are narrower stripes. This is sometimes done to increase contrast between multiple stripes or to follow the rule of tincture, though in some cases the fimbriation also has specific symbolism.