The Ecology Global Network estimates that there are about 600 million small cats in the world. This includes pets, strays, homeless and feral cats. The wild cats alone number about 100 million.
Across the globe, cats are the most popular pets. With the exception of Antarctica, cats are kept on every continent. Depending upon the classifying source, there are between 39 and 49 breeds of domestic cat.
More than 10,000 years ago in the Middle East, cats became domesticated and began controlling pests. The ancestors of pet cats began living near people, feeding on human enemies such as grain-eating rodents. During the 1940s, cats started to become common indoor pets, and kitty litter was developed to assist in this transition.