Modern zoos try not only to be for people's entertainment, but for education, research, and the conservation and protection of animals. Many zoos are centers where rare animals are preserved when they are in danger of dying out. These modern zoos also want to give the animals a natural life, so that they are healthy and behave normal. This is done for the animals, but also that people can see the animals as if they were in nature, and not in a zoo.
Zoos cost money. They educate the public on the biological diversity that makes up the world. They help people and wildlife successfully coexist. They pursue continuing research and education for people. They preserve crucial natural resources. They work to ensure zoos can provide the most natural environment possible for wildlife in its care. Without enough money they cannot do these things.
Many zoos are not like the modern type of zoo. There the animals are held in bad conditions. They are kept in small cages, and they are bored and get sick.