However, if this field is not meaningful, that is it is strictly for the database to internally identify a unique record, it is a surrogate key or blind key. In this case Person ID probably is an AutoNumber field, and it should not be used except internally by the database.
It's the city of New York that is divided into boroughs. In 1898, the modern city of New York was formed by merging the County of New York (modern day Manhattan and the Bronx), the then independent city of Brooklyn, Richmond County, and the western parts of then Queens County (the remainder is modern day Nassau County). To make people happy, the new city was divided into boroughs (similar to London). The original city of New York became Manhattan (named after the island it is on). The remainder of New York County became The Bronx. Brooklyn stayed Brooklyn. Queens County is also Queens. And Richmond County became Staten Island (also named after the island it is on).
a city in SE New York State, at the mouth of the Hudson River: the largest city and chief port of the US; settled by the Dutch as New Amsterdam in 1624 and captured by the British in 1664, when it was named New York; consists of five boroughs (Manhattan, the Bronx, Queens, Brooklyn, and Staten Island, which was called Richmond until 1975) and many smaller islands, with its commercial and financial centre in Manhattan; the country's leading commercial and industrial city.