Ireland has long had 4 Provinces, divided into 32 counties as follows:
| Leinster (East) | Munster (South) | Connacht(West) | Ulster (North) |
| Co. Carlow | Co. Clare | Co. Galway | (Rep. of Ireland) |
| Co. Dublin | Co. Cork | Co. Leitrim | Co. Cavan |
| Co. Kildare | Co. Kerry | Co. Mayo | Co. Donegal |
| Co. Kilkenny | Co. Limerick | Co. Roscommon | Co. Monaghan |
| Co. Laois | Co. Tipperary | Co. Sligo | |
| Co. Longford | Co. Waterford | (North. Ireland) | |
| Co. Louth | Co. Antrim | ||
| Co. Meath | Co. Armagh | ||
| Co. Offaly | Co. Derry | ||
| Co. Westmeath | Co. Down | ||
| Co. Wexford | Co. Fermanagh | ||
| Co. Wicklow | Co. Tyrone |
Provinces
The first Norman invaders used or adapted existing boundaries and toponyms. The most important of these were the Cuíg Cuígí (Five Fifths): Ulaidh (Ulster) in the North, Connacht in the West, Mumhain (Munster) in the South West, Laighin (Leinster) in the South East and Midhe (Meath), corresponding to the present-day counties of Meath, Westmeath, Longford, Offaly and south County Louth in present-day Leinster. (North County Louth was considered to be part of Ulster).
In 1210 King John incorporated the territory of Midhe (Meath) into Leinster for various political reasons, and Ireland thereafter was considered to have 4 Provinces.
Gradually supplanted between 1210 and 1617 by Counties, the 4 Provinces nowadays have virtually no legal significance, but retain popular status. Identified with specific counties, they are still used as political labels for gathering and presenting statistical information and certain other administrative projects.
The 4 Provinces are also still used in some sporting contexts, as the Gaelic Athletic Association and several other sports authorities run separate provincial championships, and Ireland’s four professional rugby teams play under the names of the provinces.
Counties
Counties or shires were areas under the direct jurisdiction of the Crown, administered by Sherriffs.
The counties of Ireland evolved over time, with the earliest defined being set out by Prince John, including a then much larger County Dublin. By 1200 there were also shires of Connacht, Kerry, Limerick, Louth, Tipperary and Waterford. Counties Kilkenny and Wexford apparently date from this time, too. The County of Roscommon was separated from Connacht before 1292, and the Parliament of 1297 created the new shires of Kildare, Meath and Ulster. The county of Catherlough / Caterlaugh / Caterlagh (Carlow) was probably established c.1306.
The Tudor administrations finalised the division of Ireland into counties. Westmeath was separated from Meath in 1543, and in 1556 Queen Mary established Queen’s County and King’s County in honour of herself and her husband, King Felipe II of Spain, as part of the policy of Plantation. The old shire of Connacht was broken up into the Counties of Galway, Mayo and Sligo, while Leitrim was separated from Roscommon in 1565. At the same time County Clare was created and moved from Munster to Connacht, returning in 1602. In 1583 County Longford was formed from part of Westmeath and transferred to the Province of Connacht.
The Province of Ulster was the last to be shired. The counties of Antrim and Down originated early in the C16th. These were joined in 1584/5 by the Counties of Armagh, Coleraine, Donegal, Fermanagh, Monaghan and Tyrone. County Cavan was also formed in 1584 and transferred from Connacht to Ulster.
The list of 32 counties was completed in 1606 with the shiring of County Wicklow, taking in the southern part of Dublin (with the exception of three “islands” of (mainly) church property), and the eastern part of Catherlough, including Arklow.
Former counties include: County Coleraine which formed the basis of County Derry; Nether and Upper Tyrone which were merged, and Desmond which was split between Counties Cork and an enlarged County Kerry in 1606. Until 1777 there was a County Carrickfergus, which extended further than the modern borough of that name.
County Tipperary was split into North and South Ridings in 1838 (nowadays Tipperary North and Tipperary South), and County Cork was similarly divided for judicial purposes (boundaries still echoed in several administrative and judicial arrangements).
In 1994, County Dublin was split for administrative purposes into Fingal, South Dublin and Dun Laoghaire-Rathdown.
The counties were initially used only for judicial purposes, but in 1836 their first use as local government units occurred. The Grand Jury (Ireland) Act 1836 imported a system already operating in England and Wales into Ireland. The grand jury consisted of the principal landowners of the county and had responsibility for bridges, roads and public works. The Local Government (Ireland) Act 1898 introduced elected county councils taking over the powers of the grand juries.
Ireland seems to be the only country to write county names as “Co. Tipperary, Co. Mayo etc”, and to include the word “County” as the first part of the spoken name; in times past it was usual to precede it with “the”. The word “shire” is never applied to Irish counties except as a historical verb. In England people commonly refer to “Yorkshire, Leicestershire” and plain “Middlesex, Cornwall”; in the USA citizens refer to “Orange County, Renville County” etc. The term county is used in almost all English-speaking countries and is also used to translate the equivalent units in jurisdictions as vared as Finland, Iran and Japan. While not exactly the same, the term county is arguably best translated into Spanish as comarca rather than condado.
The term county derives from the French word comté, meaning the land under the jurisdition of a comte / count, whose English counterpart is called an Earl. However, there is no particular connection between Earldoms and Counties; rather, after their 1066 seizure of the English throne, the French-speaking Normans found it convenient to apply the word to the shires, administrative divisions of the former Anglo-Saxon kingdoms. Of course, titles of nobility usually contain toponyms, but these may be chosen for sentimental or other reasons and do not necessarily indicate any official relationship between the aristocrats and the places named.
Baronies
In Ireland, a barony is a historical geographical unit, a mid-level division of land between counties and townlands. Baronies often correspond at least approximately to earlier Gaelic tuatha. A barony is normally a subdivision of a county (although some baronies straddle county boundaries as a result of historical anomalies). Some baronies established by medieval administrations were subsequently divided into two or more baronies.
The total number of baronies is 331. A figure of 273 is also quoted, by combining those divided into East/West, North/South or Upper/Middle/Lower divisions.
Baronies continue to be officially defined units, used in land registration and specifications for planning applications etc. A smaller unit, the quarter, is generally not recorded.
Although “Baron” was a title in both the Peerage of Ireland and the Peerage of the United Kingdom, the grant of such titles, as with other tites of nobility, had increasingly less to do with possesions in any geographic barony, even if it formed part of their title.
Townlands
A townland is a small geographical unit of land, believed to be of Gaelic origin. The English language term is used in Ireland and Scotland, and a similar unit exists in the Isle of Man.
In Ireland, a townland is the lowest-level officially-defined geographical unit of land, smaller than a parish, barony or county. Townlands vary in size from as small as half an acre (2,000 m²) up to more than seven thousand acres (28 km²). There are around 60,000 townlands.
Townlands form the building blocks for higher-level administrative units. Roughly equivalent to municipalities for some purposes, these are a useful reference point in parts of the country otherwise difficult to label.
The term “townland” is believed to have originated from a translation of the Gaelic word Baile, which can mean town, village, hamlet, settlement or populated place.