If you need to move your pet around on any sort of regular basis then you might be in the market for a pet carrier.
Cat carriers are ideal for moving your cat from one location to another, safely and securely. They can be in the form of carrier bags or cages or plastic crate carriers.
Dog carriers are for moving dogs and are more sturdier and larger than cat carriers. Dog crates are often metal for strength in holding your pet as well as handling the weight, particularly or larger dogs.
Pet crates or pet carriers are also used for other pets, including rabbits.
There are a LOT of varierty of pet carriers, from variety of shapes and styles to what they are constructed of. Of course, price varies accordingly :)