Brooklyn is the most populous of the five boroughs of New York City with about 2.5 million inhabitants. An independent city prior to 1898, Brooklyn developed out of the small Dutch-founded town of "Breuckelen" on the East River shore, named after Breukelen in the Netherlands. Were it still a city, and not a borough, it would be the fourth-largest city in the United States after New York City itself, Los Angeles and Chicago. Despite being part of the City of New York, Brooklyn in character is its own city, as opposed to the Bronx which historically and characteristically could be better described as a northern extension of Manhattan.
Kings County, conterminous with Brooklyn, is also the most populous county in New York. It was named in honor of King Charles II of England.
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 large diversity, population, and size.
Signs entering the borough read, "Welcome to Brooklyn: 'How sweet it is,'" referring to a popular Jackie Gleason line. And also "Welcome to Brooklyn: Home to Everyone From Everywhere." Signs leaving the borough spout the popular phrase, long associated with Brooklyn, "Fugheddaboudit." Other signs leaving Brooklyn read the infamous Yiddish quote "Oy Vey."
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http://en.wikipedia.org/wiki/Brooklyn%2C_New_York