Cat litter
Cat litter is one of any of a number of materials used in litter boxes to absorb moisture from cat feces and urine, reducing odors and rendering them more tolerable within human dwellings.
Besides absorbancy and odor control, other factors to consider in litter choice are messiness (will the cat track the litter throughout the house) and environmental factors (is it biodegradable?).
Conventional litter
One of the first commercially available cat litters was Kitty Litter, invented in 1947 and marketed by Ed Lowe. This was the first use of clay as an absorbant; prior to this time sand had been used in litter boxes.
Clumping litter
Clumping litters are made from clay, but are designed to clump together when wet and form a solid mass separate from the other litter. This solid clumped material can then be disposed of without changing the entire contents of the litter box.
Bentonite is often used to make clumping litters. Some claim that clumping litters can be harmful to pets because if it is injested or inhaled it swells and solidifies. For the same reason it is not recommended to flush clumping litters down the toilet.
Alternative litter
Silica gel litter, a porous granular form of sodium silicate, has the highest absorbancy of any litter, and has excellent moisture and odor control.
