Brooklyn is one of the five boroughs of New York City. An independent city until its consolidation with New York in 1898, Brooklyn is New York's most populous borough, with nearly 2.5 million residents. The borough of Brooklyn is coterminous with Kings County, which is also the most populous county in New York State. As an independent city Brooklyn would rank as the fourth most populous in the United States. It was named in honor of King Charles II of England, which is the source of Brooklyn's nickname as the "City of Kings."

In spite of its consolidation with New York, Brooklyn maintains a strongly distinct character of its own. Variously called the "City of Trees," "City of Homes," or the "City of Churches" in the 19th century, Brooklyn is now often styled the "Borough of Homes and Churches" or even sometimes called "The Planet," popularized by Guru from the rap duo Gangstarr, for its diversity, large population, and size.