While cats do a good job of grooming themselves there are good reasons for you to groom your cat.
1. Brushing sitmulates new hair growth and removes dead hair.
2. If your cat swallowing to much hair when grooming themselves they can get hairballs, which can be a health concern if the hairball becomes impacted in the intestine.
So brushing your cat frequently with a brush or grooming mitt will reduce the amount of hair your cat will consume.
Tools for grooming:
For short or medium hair use a flea comb and a slicker brush,fine tooth comb or grooming glove. For long haired cats use a pin brush or fine toothed comb and a detangling spray.