Traditionally, Ireland is subdivided into four provinces: Connacht (west), Leinster (east), Munster (south), and Ulster (north). In a system that developed between the 13th and 17th centuries, Ireland has thirty-two traditional counties. Twenty-six of the counties are in the Republic of Ireland and six counties are in Northern Ireland. The six counties that constitute Northern Ireland are all in the province of Ulster (which has nine counties in total). As such, Ulster is often used as a synonym for Northern Ireland, although the two are not coterminous.
In the Republic of Ireland, counties form the basis of the system of local government. Counties Dublin, Cork, Limerick, Galway, Waterford and Tipperary have been broken up into smaller administrative areas. However, they are still treated as counties for cultural and some official purposes, for example post and by the Ordnance Survey Ireland. Counties in Northern Ireland are no longer used for local governmental purposes, but, as in the Republic, their traditional boundaries are still used for informal purposes such as sports leagues and in cultural or tourism contexts as well as in addresses.
SOURCE:http://www.gearthhacks.com/ , http://www.wikipedia.org/