Subject to qualifications which are discussed below, a country house will once have been the centrepiece of an agricultural estate large enough to provide the landowner with sufficient income to be accepted as a member of either the aristocracy or the gentry. In the 19th century and earlier this generally required an estate of at least a thousand acres (4 km²) of land. A few landowners owned more than a hundred times this minimum, and this inequality within the ruling class is reflected in the range of country houses which were built.
A country house may be built in any architectural style. It will probably have at least 25 rooms and at least 8,000 square feet (740 m²) of floor space, including service rooms. There are many designations which are used by a large number of houses, such as "house", "hall", "castle", "park", "palace", "court", "abbey", "priory", or "grange", and this often reveals something about its history, especially if it originated before 1800. On the other hand, the name may have been chosen on the whim of the owner, especially if the house was built after 1800. For example, many country houses which are designated "castle" never had any military purpose.
Most country houses have large grounds comprised of a garden in the immediate vicinity of the house, and a larger park beyond the garden which is grazed by animals, but also has aesthetic and recreational purposes. Many of the finest gardens in Britain are country house gardens.
A country house is typically several hundred metres from any other houses, but it may be close to the centre of a village or even close to the centre of a small town. (The larger the settlement the larger the house will need to be to retain its status as a "country house"-Alnwick Castle is an example of a very large house which is in a town, but is generally perceived to be a country house.)
On the other hand, some large houses in Britain that were built in rural locations are now surrounded by suburban sprawl. However, these may still be referred to as country houses in some contexts, especially by architectural historians. Syon Park in the suburbs of London is an example of this.
In Britain and Ireland, the term country house is not simply a house in a rural location. It generally refers to a large house, large enough to be regarded as a mansion, which was built on an agricultural estate as the private residence of the landowner. There are several types of smaller houses which are common in the British countryside, but are not "country houses" in the sense in which the term is generally used, these include farmhouses, cottages, rectories, oast houses and barn conversions; anyone who owns one of these and refers to it as their "country house" is likely to be considered extremely pretentious by most people in Britain. (Current usage errs towards the opposite tendency of referring to medium-sized
