Facts at a Glance about Brooklyn1. Brooklyn New York is part of New York City, which is in New York State. Brooklyn is one of the five boroughs of New York City. It is not the largest NYC borough geographically (the borough of Queens is), but Brooklyn is the most populous New York City borough.(See How many people live in Brooklyn?)
2. Brooklyn is in Kings County. Every borough of New York City is a different county. Brooklyn is known as Kings County for tax and other official purposes. Kings County is Brooklyn, and vice versa; they are one and the same. So, if someone says they are doing business in Kings County, they are doing business in Brooklyn.
Note: Brooklyn is not part of New York County, which is contiguous with Manhattan.