The townland is an ancient geographic unit, which dates from before Norman times. It is used in Ireland, and is the smallest administrative division still in use throughout the island. Townland an approximate English translation of baile (or bally), which means home, settlement, or village.

Ireland's counties divide into baronies, baronies into parishes, and parishes into townlands, which once had the further subdivisions of gneeves and ploughlands, but no longer. Ireland is made up of some 62000 townlands. The shape and size of a townland may vary greatly, in that their these are related to the local topography, and to farming practices. A civil parish may be made of from five to thirty different townlands. From the 17th century, landlords let their land by the townland. Estate rental, Tithe Applotment, and Census texts all recorded the townland as the smallest division.

Using baile as the original Irish word, some larger townlands were called ballybetaghs, which, in Ireland's north, were usually divided into a dozen ballyboes, or, in the areas of Fermanagh and Monaghan, into sixteen tates. In the original Irish, many townland's names referred to geopgraphic features (Carraig:rock, Tullagh:hill, Annagh:marsh). Some townlands may be named after the families that held these lands before plantations became the norm; there are such townlands as Ballygraffan, Ballybunden, and Ballywalter. Other townlands are named after early habitations, and include words such as Dun or Rath (hill or fortification), and Chill, Kill, or Kil (church).

Accurately spelling townland names in English is difficult in that they were named in the Irish; there are sometimes multiple English names for a given place, and over the passage of time, as English court scribes wrote and rewrote the townland names, they became increasingly phoenetically anglicized.

In 1904, William Butler Yeats wrote a poem, "The Happy Townland".