Pest is a county (vármegye) in central Hungary. It covers an area of 6,393.14 square kilometres (2,468.41 sq mi), and has a population of 1,339,090 (2023). It surrounds the national capital Budapest and the majority of the county's population live in the suburbs of Budapest. It shares borders with Slovakia and the Hungarian counties Nógrád, Heves, Jász-Nagykun-Szolnok, Bács-Kiskun, Fejér, and Komárom-Esztergom. The River Danube flows through the county. The capital of Pest County is Budapest, although Budapest is not part of Pest County. Starting 2018, they also constitute different NUTS:HU level 2 regions, as previously Pest County has lost catch-up aids from the European Union because of the high development of Budapest.

Budapest is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and it was the largest city on the Danube river; today it is the second largest one. The city has an estimated population of 1,752,286 over a land area of about 525 square kilometres. Budapest, which is both a city and municipality, forms the centre of the Budapest metropolitan area, which has an area of 7,626 square kilometres and a population of 3,303,786. It is a primate city, constituting 33% of the population of Hungary.