Dayton is a city in southwestern Ohio, United States. It is the county seat and largest city of Montgomery County. As of the 2005 census estimate, the population of Dayton was 158,873. The Dayton metropolitan area, or Greater Dayton, which includes the communities of Vandalia, Clayton, Englewood, Oakwood, Bellbrook, Trotwood, Kettering, Piqua, Tipp City, Centerville, Beavercreek, Fairborn, West Carrollton, Huber Heights, Troy, Riverside, and Miamisburg, had a population of 843,577 as of the 2005 estimate. Dayton is situated within the Miami Valley region of Ohio, just north of the Cincinnati metropolitan area.

Dayton plays host to significant industrial, aerospace, and technological/engineering research activity and is known for the many technical innovations and inventions developed there. The city was the home of the signing of the Dayton Peace Accords, which brought an end to the war in Bosnia. The Wright brothers, poet Paul Laurence Dunbar, and entrepreneur John H. Patterson were born in Dayton. The Dayton area is home to several major international, national, and regional corporations, including NCR, Reynolds & Reynolds, ChemStation International, Liberty Bank, NewPage Corporation, Standard Register, WorkflowOne (formerly Relizon), Huffy Bicycles, LexisNexis, and Mead prior to becoming MeadWestvaco. It was formerly home of Speedwell Motor Car Company.