A flag is a piece of cloth, often flown from a pole or mast, generally used symbolically for signaling or identification. The term flag is also used to refer to the graphic design employed by a flag, or to its depiction in another medium.

The first flags were used to assist military coordination on battlefields, and flags have since evolved into a general tool for rudimentary signaling and identification, it was especially used in environments where communication is similarly challenging (such as the maritime environment where semaphore is used). National flags are potent patriotic symbols with varied wide-ranging interpretations, often including strong military associations due to their original and ongoing military uses. Flags are also used in messaging, advertising, or for other decorative purposes. The study of flags is known as

vexillology, from the Latin vexillum meaning flag or banner.

The Flag of Ireland is the national flag of Ireland^[1][2] (Irish: An Bhratach Náisiúnta), also known as the tricolour,^[3] and is a vertical tricolour of green (at the hoist), white, and orange. The flag proportion is 1:2 (length twice the width). The green represents a Gaelic tradition while the orange represents the supporters of William of Orange. The white in the centre signifies a lasting truce between the 'Orange' and the 'Green'.^[4]

First introduced by Thomas Francis Meagher in 1848, it was not until the Easter Rising of 1916, when it was raised above the General Post Office, along with a green flag with words Irish Republic in Dublin, that the tricolour came to be regarded as the national flag.^[5] Meagher was the son of Newfoundland-born mayor of Waterford, Ireland, Thomas Meagher, Jr., and his flag was inspired by the similarly-symbolic Newfoundland Tricolour created in 1843.^[6][7]

The flag was adopted in 1919 by the Irish Republic during its war of independence, and subsequently by the Irish Free State (1922–1937), later being given constitutional status under the 1937 Constitution of Ireland. The tricolour is regarded by many nationalists as the national flag of the whole of island of Ireland. Thus it is flown (often controversially) by many nationalists in Northern Ireland as well as by the Gaelic Athletic Association.^[8] The shorter flag of Côte d'Ivoire's colours are the same but reversed in order.