Today marks 170 years since the tricolour was first flown publicly.
Irish patriot Thomas Francis Meagher raised what would later become the national flag at the Wolfe Tone Confederate Club at 33 The Mall in Waterford city in 1848.
Mr Meagher was born in Waterford and became one of the leaders of the Young Irelanders in 1848.
In April of that year he stated that: "The white in the centre signifies a lasting truce between Orange and Green and I trust that beneath its folds the hands of Irish Protestants and Irish Catholics may be clasped in generous and heroic brotherhood."
It was adopted as the flag of the Irish Free State in 1922 and formally confirmed as the national flag in the 1937 Constitution.
To celebrate the flag's birthday, the GPO Witness History Centre in Dublin is hosting an exhibition on the Irish Flag.