Northern Ireland is a constituent unit of the U.K., known for its friendliest of welcomes, Norman castles, glacial valleys and mountains, Celtic and Christian monuments, and renowned coastal links golf courses. It is variously described as a country, province, region, or "part" of the United Kingdom, amongst other terms.
Northern Ireland was created in 1921, when Ireland was partitioned between Northern Ireland and Southern Ireland by an act of the British parliament. It comprises six of the nine counties of Ulster (one of the four ancient Irish provinces), with the remaining three (Monaghan, Cavan and Donegal) staying in what is now the modern day Republic of Ireland. For this reason Ulster is a popular colloquial alternative name for Northern Ireland, even if it is not in the strictest sense historically accurate.