Brooklyn is the most populous of New York City's five boroughs, with approximately 2.5 million residents, and the second-largest in area. Since 1896, Brooklyn has had the same boundaries as Kings County, which is now the most populous county in New York State and the second-most densely populated county in the United States, after New York County (Manhattan). It is also the westernmost county on Long Island.

Brooklyn was an independent city until it was annexed by New York City in 1898. It continues to maintain a distinct culture. Many Brooklyn neighborhoods are ethnic enclaves where particular ethnic groups and cultures predominate.

Brooklyn's official motto is Eendraght Maeckt Maght. Written in the (early modern spelling of the) Dutch language, it is inspired by the motto of the United Dutch Provinces and translated "Unity makes strength". The motto is displayed on the borough seal and flag, which also feature a young robed woman bearing fasces, a traditional emblem of republicanism. Brooklyn's official colors are blue and gold.