One Common Usage of the Term "Exotic Pets"
In many situations, an exotic pet is loosely defined as any pet that is not a dog, cat, fish or horse. In this usage, the term exotic pet is a convenient catch-all phrase used to describe "non-traditional" pets. For example, you may have to find an veterinarian specializing in exotic pets if you have pets other than cats, dogs, or horses. Using this definition, many domestic animals fall into the category of exotic pets, even though they may have been domesticate for thousands of years, like ferrets. I guess in this sense, exotic just means "a bit unusual."
Exotic Pets at About.com
Here at About.com there are pet sites for cats, dogs, fresh water fish, salt water fish, pet birds and horses. Everything else falls under the umbrella of the exotic pets site. Indeed, you will find the emphasis here mostly on domesticated pets that are just a bit out of the ordinary, such as rabbits, ferrets, hamsters, guinea pigs, etc. You will also find some reptiles and amphibians, insects, spiders and crabs - generally only those that are commonly seen in the pet trade and ideally only those that breed readily in captivity. In fact, I would prefer that animals not be taken from the wild to be kept as pets at all.
Problems with Exact Definitions of Exotic Pets
The term exotic is generally used to describe something that is foreign, or something different or unusual. The problem with using foreign is that it is a relative term so is not a precise definition in itself. "Different" and "unusual" are problematic as a definition too. Some pets included in the common usage of "exotic pet" are not really that unusual (e.g rabbits, ferrets, hamsters and guinea pigs are pretty widely accepted as pets), but it is still common practice to categorize them as exotic pets since they are not as common as pets as cats and dogs.
Some people define exotic pets as anything that is "wild" or not domesticated. However, this is not a precise definition either, since there is not an exact definition of the time when an animal that is tame and/or has been bred in captivity crosses the line from wild to domestic.
So, the definition of exotic pet is complicated and open to interpretation. This is certainly the case when it comes to laws governing keeping of exotic pets, and why I always recommend checking the laws where you live. What is considered exotic or subject to regulatory laws varies from location to location (see Legal Issues for more about laws).
But Why are Llamas, Alpacas and Goats Included On This Site?
Some readers have questioned the inclusion of these animals on this exotic pets site (seeing as they are domestic and not typically kept as a "pet"). However, I found there was an interest in these animals as companions and some owners do consider them pets. Mostly, though, they don't really fit into the other sites at About so I made room for them here for those who are interested in keeping them as companions.