Taken from Wikipedia

Tarantula is the common name for a group of hairy, sometimes very large spiders belonging to the family Theraphosidae, of which 800 species have been identified. Tarantulas hunt prey on the ground and do not spin webs. They mainly eat insects and other arthropods, caught by speed or ambush. The biggest tarantulas can kill animals as large as lizards, mice, or birds. Most tarantulas are harmless to humans, and some species are kept as pets or eaten as food. These stocky, fearsome-looking spiders are found in tropical and desert regions around the world.

The name tarantula comes from the town of Taranto in Italy and was originally used for an unrelated species of European spider. (See Wolf spider for more information about this spider). In North America the term tarantula commonly refers to species of theraphosids found in the Americas. In Africa, theraphosids are often called baboon spiders. Asian forms are known as earth tigers or bird spiders. Australians refer to their species as barking spiders, whistling spiders, or bird spiders. People in other parts of the world also apply the general name mygales to theraphosid spiders.