A zoo or zoological park is a place where animals are kept in some form of cage to be viewed by human beings in a safe environment. Some zoos are open-air, and some keep animals in fairly enclosed spaces. A special kind of zoo is the petting zoo, where people and children are allowed to touch and pet the animals.
Petting zoos typically include llamas, goats, and kangaroos (in Australia).
The most famous zoos in the world are probably the San Diego Zoo, the Berlin Zoo, the London Zoo, the Woodland Park Zoo in Seattle, and the National Zoo in Washington, D.C..