Cats mat. It is a fact. It doesn’t matter whether the cat in question has long hair or short hair or is purebred or domestic – its coat will get matted over time.  
While regular combing will help prevent matting, the best defence is a thorough degreasing bath and blow-dry. This is where the professional cat groomer comes in. 
Cats are naturally oily. Their skin produces oil that spreads throughout the coat if given enough time. Some cats are greasier than others and some become greasier with time, especially if they have certain health issues. 
Cats naturally shed. This is true regardless of coat length. In fact, short-hair cats usually shed more than long-hair breeds. As the hair sheds, the greasiness of the coat makes it gummy enough to cause some of the shedding hair to stick to the hair that is not shedding. This, in turn, creates a small tangle. 
Usually, these small tangles are imperceptible; with time, though, hair continues to shed under and around the tangle. Instead of falling away, it sticks to the existing tangle, making it bigger. At this point, the tangle becomes a mat. Several mats can form at one time in various places on a cat’s body.  
Eventually, if left untreated, these mats will form one giant pelt. The pelt may also begin to pull closer to the skin at this point. If too much time goes by before it is removed, the pelt will be so close to the skin that sores can develop underneath. 
Remember: cats don’t groom themselves – they lick themselves. Licking does nothing to remove mats, kill fleas, eliminate dandruff, deodorize, correct bad breath, kill germs, trim sharp nails, or clean up messes. If we licked ourselves all over, we wouldn’t be clean – we’d be covered in saliva!