Charleston is the second largest city in the United States state of South Carolina. It was made the county seat of Charleston County in 1901 when Charleston County was founded. The city's original name was Charles Towne in 1670, and it moved to its present location (Oyster Point) from a location on the west bank of the Ashley River (Albemarle Point) in 1680. It adopted its present name in 1783. In 1690, Charleston was the fifth largest city in North America, and remained among the ten largest cities in the United States through the 1840 census. As defined by the U.S. Office of Management and Budget, and used by the U.S. Census Bureau for statistical purposes only, Charleston is included within the Charleston – North Charleston – Summerville metropolitan area and the Charleston-North Charleston urban area.

Charleston is known as The Holy City due to the prominence of churches on the low-rise cityscape, particularly the numerous steeples which dot the city's skyline, and for the fact that it was one of the few cities in the original thirteen colonies to provide religious tolerance, albeit restricted to non-Catholics. Many Huguenots found their way to Charleston. Charleston was also one of the first colonial cities after Savannah, Georgia to allow Jews to practice their faith without restriction. Kahual Kadosh Beth Elohim, founded in 1749, is the fourth oldest Jewish congregation in the continental United States. Brith Sholom Beth Israel is the oldest Orthodox synagogue in the South, founded by Ashkenazi (German and Central European Jews) Jews in the mid-19th century.
The population was counted by the U.S. Census in 2010 at 120,083, making it the second most populous city in South Carolina, closely behind the state capital Columbia. Current trends put Charleston as the fastest-growing municipality in South Carolina. The city is one of three principal cities of a metropolitan statistical area of 659,191—the second largest in the state—and the 76th – largest metropolitan statistical area in the United States.

The city of Charleston is located just south of the mid-point of South Carolina's coastline, at the confluence of the Ashley and Cooper rivers, which flow together into the Atlantic Ocean. Charleston Harbor lies between downtown Charleston and the Atlantic Ocean. Charleston's name is derived from Charles Towne, named after King Charles II of England.

America's most-published etiquette expert, Marjabelle Young Stewart, recognized Charleston 1995 as the "best-mannered" city in the U.S, a claim lent credibility by the fact that it has the first established Livability Court in the country.