CountrySide is a census-designated place in Loudoun County, Virginia. The population as of the 2010 United States Census was 10,072. CountrySide is located about northwest of Washington and is bounded by the Potomac River to the north, and by Route 7 (Leesburg Pike) to the south. Located in eastern Loudoun County, it is about from Washington Dulles International Airport.

In general, a rural area or countryside is a geographic area that is located outside towns and cities. The Health Resources and Services Administration of the U.S. Department of Health and Human Services defines the word "rural" as encompassing "...all population, housing, and territory not included within an urban area. Whatever is not urban is considered rural."