County Armagh is one of the six counties of Northern Ireland and one of the traditional thirty-two counties of Ireland. It is located in the province of Ulster and adjoins the southern shore of Lough Neagh. It borders the Northern Irish counties of Tyrone to the west and Down to the east. The county borders Louth and Monaghan to the south and southwest, which are in the Republic of Ireland. It is named after its county town, Armagh, which derives from the Irish Ard Mhacha, meaning "Macha's height". Macha was a sovereignty goddess in Irish mythology and is said to have been buried on a wooded hill around which the town of Armagh grew. County Armagh is colloquially known as the "Orchard County" because of its many apple orchards.

Ulster is one of the four traditional or historic Irish provinces. It is made up of nine counties: six of these constitute Northern Ireland ; the remaining three are in the Republic of Ireland.