Bratach na hÉireann - Vicipéid:

Is í an Bhratach Náisiúnta bratach na hÉireann. B'í bratach Saorstát Éireann agus nuair a bunaíodh Poblacht na hÉireann tugadh stádas bunreachtúil dó. Is iad an uaine, an bán, agus an flannbhuí, na dathanna. Seasann rogha na ndathanna seo don tsíocháin idir Protastúnaigh (flannbhuí) agus Caitlicigh (glas/uaine). Tá an bhratach á húsáíd ón mbliain 1919 i leith.

From Flag of the Republic of Ireland :

The flag of the Republic of Ireland is the national flag of the Republic of Ireland (Irish: An Bhratach Náisiúnta), also known as the tricolour. It 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'.

The Irish Constitution says, "The national flag is the tricolour of green, white and orange." The Irish Government defines the offical colours as Pantone 347 green (equivalent to hexadecimal colour code #009A49) and Pantone 151 orange (code #FF7900).

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 in Dublin, that the tricolour came to be regarded as the national flag. 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. Historically the island has been represented by a number of other flags, including Saint Patrick's cross, and the flag of the four provinces of Ireland.