The national flag of the Netherlands is a horizontal tricolour of red, white, and blue. The current design originates as a variant of the late 16th century orange-white-blue Prinsenvlag, evolving in the early 17th century as the red-white-blue Statenvlag, the naval flag of the States-General of the Dutch Republic, making the Dutch flag the oldest tricolour flag in continuous use. As a flag that symbolises the transformation from monarchy to republic, it has inspired both the derivative Russian flag, and after the French Revolution in 1789, the vertically striped French tricolour; both flags in turn influenced many other tricolours. During the economic crisis of the 1930s, the old Prince's Flag with the colour orange gained some popularity among some people. To end the confusion, the colours red, white and blue and its official status as the national flag of the Kingdom of the Netherlands were reaffirmed by royal decree on 19 February 1937.

A national flag is a flag that represents and symbolizes a given nation. It is flown by the government of that nation, but can also be flown by its citizens. A national flag is typically designed with specific meanings for its colours and symbols, which may also be used separately from the flag as a symbol of the nation. The design of a national flag is sometimes altered after the occurrence of important historical events. The burning or destruction of a national flag is a greatly symbolic act.