The Bronx Zoo is located in the Bronx borough of New York City, within Bronx Park. It is one of the world's largest metropolitan zoos, with over 600 species from around the world. The zoo comprises 265 acres (107 ha) of park lands and naturalistic habitats, through which the Bronx River flows.

The Bronx Zoo is part of an integrated system of four zoos and one aquarium managed by the Wildlife Conservation Society (WCS), and is accredited by the Association of Zoos and Aquariums (AZA).

Fordham University owned the land which became the Bronx Zoo and New York Botanical Garden. Fordham sold it to the City of New York for only $1,000 under the condition that the lands be used for a zoo and garden; this was in order to create a natural buffer between the university grounds and the urban expansion that was nearing. In the 1880s, New York State set aside the land for future development as parks. In 1895, New York State chartered the New York Zoological Society (later renamed to Wildlife Conservation Society) for the purpose of founding a zoo.

The Bronx is the northernmost of the five boroughs of New York City. It is also known as Bronx County, the last of the 62 counties of New York State to be incorporated. Located north of Manhattan and Queens, and south of Westchester County, the Bronx is the only borough that is located primarily on the mainland (a very small portion of Manhattan, the Marble Hill neighborhood, is physically located on the mainland, due to the rerouting of the Harlem River in 1897). The Bronx's population is 1,400,761 according to the 2010 United States Census. The borough has a land area of 42 square miles (109 km²), making it the fourth-largest in land area of the five boroughs, the fourth most populated, and the third-highest in density of population.

The Bronx is divided by the Bronx River into a hillier section in the west, closer to Manhattan, and the flatter East Bronx, closer to Long Island. The West Bronx was annexed to New York City (then largely confined to Manhattan) in 1874, and the areas east of the Bronx River in 1895. The Bronx first assumed a distinct legal identity when it became a borough of Greater New York in 1898. Bronx County, with the same boundaries as the borough, was separated from New York County (afterwards coextensive with the Borough of Manhattan) as of January 1, 1914. Although the Bronx is the third-most-densely-populated county in the U.S., about a quarter of its area is open space, including Woodlawn Cemetery, Van Cortlandt Park, Pelham Bay Park, the New York Botanical Garden and the Bronx Zoo in the borough's north and center, on land deliberately reserved in the late 19th century as urban development progressed northwards and eastwards from Manhattan with the building of roads, bridges and railways.

A zoo (short for zoological park or zoological garden, and also called a menagerie) is a facility in which animals are confined within enclosures, displayed to the public, and in which they may also be bred.

The term zoological garden refers to zoology, the study of animals, a term deriving from the Greek zōon (ζῷον, "animal") and lógos (λóγος, "study"). The abbreviation "zoo" was first used of the London Zoological Gardens, which opened for scientific study in 1828 and to the public in 1847. The number of major animal collections open to the public around the world now exceeds 1,000, around 80 percent of them in cities.

However, keeping animals in zoos raises concerns for animals rights.

Zoos typically house more wild animals than domesticated ones.

London Zoo, which opened in 1828, first called itself a menagerie or "zoological garden," which is short for "Gardens and Menagerie of the Zoological Society of London." The abbreviation "zoo" first appeared in print in the UK around 1847, when it was used for the Clifton Zoo, but it was not until some twenty years later that the shortened form became popular in the song "Walking in the Zoo on Sunday" by music-hall artist Alfred Vance. The term "zoological park" was used for more expansive facilities in Washington, D.C., and the Bronx in New York, which opened in 1891 and 1899 respectively.