(1) Wild animals have been kept in captivity for thousands of years, often as symbols of power or religious significance. (2) However, what is now recognized as the modem zoo was developed in the early part of the 19th century with London, Paris and Dublin zoos opening within a few years of each other. (3) This coincided with the Victorian fascination with natural history and increasing urbanization of the population of Europe, and these 19th century zoos proved to be immensely popular, with millions flocking to see unusual animals from far off lands. (4) The majority of zoos served simply to display animals, with the more advanced among them, also utilizing their collections for the study of zoology. (5) By visiting zoos people make a direct contribution through entry tickets to maintaining the threatened species in zoos. (6) However, over time good zoos have changed their mission and focus due to a growing realization and documentation of the decline in wildlife, driven mostly by loss of habitat. (7) From the mid-20th century these zoos have been finding ways to help conserve wild animals and their habitats, and the animals now fulfill a number of roles, from education to ambassadors for their species.