A feeling of rough sandpaper as you are licked by your cat is a reminder that its long muscular tongue serves many functions, including grooming.
A cat's ability to groom itself is the result of numerous knobs called papillae, on the surface of a cat's tongue. Located at the tongue's center, the papillae form backward facing hooks containing large amounts of keratin, the same material found in human fingernails. These hooks provide the abrasiveness a cat needs for self grooming. The strengh of these hooks also helps a cat hold food or struggle with prey.
Although the abrasiveness of a cat's tongue helps it to clean itself and untangle its hair, your help is needed through regular grooming. As you groom your cat, you are removing loose and dead hair. Otherwise a cat may ingest this hair and hair balls can form which can cause vomiting and may cause impaction in the gastrointestinal tract. Long haired cats need daily grooming, short haired cats should be groomed at least once a week.