A zoo is a large park where wild animals are on display. If you're interested in lemurs, orangutans, or even boa constrictors, you might want to plan a trip to the zoo.
Most modern zoos serve two functions: to exhibit exotic animals for paying visitors and to protect endangered animal species. Responsible zoos fulfill the second goal by breeding animals, educating the public, and reintroducing animals to the wild. Any wild and crowded place can also be called a zoo: "I went to the mall the day before Christmas. It was a total zoo!" The word zoo, from a Greek root that means "animal," was originally shorthand for the Regent's Park Zoological Gardens in London, which opened in 1828.