A cat tree is an artificial structure for a cat

Cat

The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...

 to play

Cat play and toys

Cat play and toys incorporates predatory games of "play aggression". These activities allow kittens and younger cats to grow and acquire cognitive and motor skills, and to socialize with other cats...

, exercise and relax on. Cat trees vary in height with cats preferring ones that are tall enough to allow them to see everything in their environment. Cat trees are usually constructed of wood and then covered with carpet

Carpet

A carpet is a textile floor covering consisting of an upper layer of "pile" attached to a backing. The pile is generally either made from wool or a manmade fibre such as polypropylene,nylon or polyester and usually consists of twisted tufts which are often heat-treated to maintain their...

 or a similar fabric that encourages and allows a cat to scratch. Cat trees are often used specifically to prevent scratching of other household items. In addition to carpet, trees may contain other desirable items to encourage scratching of the tree such as sisal

Sisal

Sisal is an agave that yields a stiff fibre traditionally used in making twine, rope and also dartboards. The term may refer either to the plant or the fibre, depending on context...

rope, and cat toys.

Cat trees are named as such because they typically have several platforms at differing angles that aid in exercise for the cat as well as a means for the cat to reach the top. The term 'condo' is based on more extensive cat trees that contain enclosed areas for the cat to hide in.