Cat litter is designed to serve a purpose. It deals with urine and solid waste so feline companions can live comfortably with their humans. There are two basic categories under which most litter can be placed: clumping and non-clumping. Clumping litter is made to harden upon contact with liquid. One of the best clumping clay litters on the market is Dr. Elsey's Precious Cat Ultra Premium Clumping Litter. Litter boxes are freshened up by scooping out the hard clumps. Non-clumping litter relies on its absorptive powers. Feline Pine is a non-clumping natural biodegradable choice that can even be use with kittens. The best of both worlds can be found in clumping biodegradables like SmartCat All Natural Clumping Litter. Many factors come into play when choosing a litter, some of which will be in direct relation to the cats' preferences, some of which will be based on human factors like available space and number of boxes set-up.