Short answers, pulled from the story.
Lagos is a large metropolitan port city in southwestern Nigeria, sitting at the southwest mouth of Lagos Lagoon and protected from the Atlantic Ocean by barrier islands and sand spits. It is the most populous urban area on the African continent, with population estimates between 17 and 21 million residents.
Lagos was the national capital of Nigeria until the government's December 1991 decision to relocate the capital to Abuja in the centre of the country. Abuja officially became the capital on the 12th of December 1991, though the decision had been made fifteen years earlier in Act No. 6 of 1976.
Lagos is derived from the Portuguese word for lakes. It was most likely named after Lagos, Portugal, the main centre of Portuguese maritime expeditions down the African coast in the 15th century. The native Yoruba name Eko, meaning farmstead, is also used by Yoruba people.
Population estimates for Lagos range between 17 and 21 million residents, though the figure is disputed. The 2006 federal census credited Metropolitan Lagos with about 7.9 million people, while the Lagos State Government's own parallel census put the wider state figure at over 17.5 million.
Lagos is called Africa's Silicon Valley because it is home to more tech hubs than any other city in Africa and hosts five of the seven African tech unicorns, including Flutterwave, Opay, Interswitch, Andela, and Jumia. It is the only African city to have both a Google and a Microsoft office.
Lagos generates around 30-35% of Nigeria's GDP and serves as the country's major financial and banking centre. The four largest banks in West and Central Africa are headquartered there, including Zenith Bank, Access Bank, Guaranty Trust Bank, and First Bank, each with capital over US$2 billion.
The 2022 IPCC Sixth Assessment Report named Lagos among 12 major African cities most severely affected by sea level rise. The threat is worsened by subsidence occurring at up to 87 mm per year, and a 2019 study projected that by 2050 Lagos would resemble the current climate of Panama City.