What is the Manhattan?
Manhattan is a borough of New York, New York, USA, coterminous with New York County
The borough Manhattan consists of Manhattan Island, Roosevelt Island, Randalls Island, almost 1/10th of Ellis Island , the above-water portion of Liberty Island, several much smaller islands - Belmont Island, and a small section on the mainland - Mill Rock adjacent to the Bronx.
Manhattan's many neighborhoods are not named according to any particular convention. Some are geographical (the Upper East Side), or ethnically descriptive (Chinatown). Others are acronyms, such as TriBeCa (for "TRIangle BElow CAnal Street") or SoHo ("SOuth of HOuston"), or the far more recent vintage NoLIta ("NOrth of Little ITaly"). Harlem is a name from the Dutch colonial era after Haarlem, a city in the Netherlands. Some neighborhoods, such as SoHo, are commercial in nature and known for upscale shopping. Others, such as Greenwich Village, the Lower East Side and the East Village, have long been associated with the "Bohemian" subculture. Chelsea is a neighborhood with a large gay population, and also recently a center of New York's art industry and nightlife. Washington Heights is a vibrant neighborhood of immigrants from the Dominican Republic. Manhattan's Chinatown has a dense population of people of Chinese descent. The Upper West Side is often characterized as more intellectual and creative, in contrast to the old money and conservative values of the Upper East Side, one of the wealthiest neighborhoods in the United States. In Manhattan, uptown means north (more precisely north-northeast, which is the direction in which the island and its street grid system is oriented) and downtown means south (south-southwest).
This usage differs from that of most American cities, where downtown refers to the central business district. Manhattan has two central business districts, the Financial District at the southern tip of the island, and Midtown Manhattan. The term uptown also refers to the northern part of Manhattan (generally speaking, above 59th Street) and downtown to the southern portion (typically below 14th Street), with Midtown covering the area in between, though definitions can be rather fluid depending on the situation. Fifth Avenue roughly bisects Manhattan Island and acts as the demarcation line for east/west designations (e.g., East 27th Street, West 42nd Street); street addresses start at Fifth Avenue and increase heading away from Fifth Avenue, at a rate of 100 per block in most places. South of Waverly Place in Manhattan, Fifth Avenue terminates and Broadway becomes the east/west demarcation line. Though the grid does start with 1st Street, just north of Houston Street (pronounced HOW-stin), the grid does not fully take hold until north of 14th Street, where nearly all east-west streets use numeric designations, which increase from south to north to 220th Street, the highest numbered street on the island.