Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County. According to the 2000 Census, its population is 791,926, making it Indiana's most populous city and the 12th largest city in the U.S. The U.S. Census July 1, 2004 estimate for the Consolidated City of Indianapolis is 794,160 and a metropolitan area population of 1,595,377. The larger combined statistical area (an agglomeration called the Nine-County Region) has a population approaching 2 million residents (1,939,349). Indianapolis is the third largest city in the midwest after Chicago and Detroit and is one of only three major cities in the midwest which had a growth rate above 5%. As of 2004, Marion County's population is 863,596, and in 2006, the city was voted tenth of two hundred Best U.S. Metropolitan Areas for Business and Careers by Forbes Magazine.

Jeremiah Sullivan, a judge of the Indiana Supreme Court, invented the name Indianapolis by joining Indiana with polis, the Greek word for city.