Lagos (ˈleɪɡɒs ; also US: ˈlɑːgoʊs ;Èkó) or Lagos City is the most populous city in Nigeria, with an estimated population of 21 million in 2015. The estimated population for Lagos was more than 26 million in 2023; and around 30 million for the Lagos metropolitan area. Lagos is the most populous urban area in Africa. Lagos was the national capital of Nigeria until December 1991 following the government's decision to move their capital to Abuja in the centre of the country. Lagos is a major African financial centre and is the economic hub of Lagos State and Nigeria at large. The city has been described as the cultural, financial, and entertainment capital of Africa, and is a significant influence on commerce, entertainment, technology, education, politics, tourism, art, and fashion. Lagos is also among the top ten of the world's fastest-growing cities and urban areas. The megacity has the fourth-highest GDP in Africa and houses one of the largest and busiest seaports on the continent. The Lagos metropolitan area is a major educational and cultural centre in Sub Saharan Africa. Due to the large urban population and port traffic volumes, Lagos is classified as a Medium-Port Megacity.
Lagos emerged as a home to the Awori subgroup of the Yoruba of West Africa islands, which are contained in the present day Local Government Areas (LGAs) of Lagos Island, Eti-Osa, Amuwo-Odofin and Apapa. The islands are separated by creeks, fringing the southwest mouth of Lagos Lagoon, while being protected from the Atlantic Ocean by barrier islands and long sand spits such as Bar Beach, which stretch up to east and west of the mouth. Due to rapid urbanisation, the city expanded to the west of the lagoon to include areas in the present day Lagos Mainland, Ajeromi-Ifelodun, and Surulere. This led to the classification of Lagos into two main areas: the Island, which was the original city of Lagos, and the Mainland, which it has since expanded into.