There are different types of cat food:
Complete- is food that contains all the nutrients your cat needs every day (yep, all 41 of them)
Complementary- is food that only contains some of what your cat need every day so they will other food as well (a cat treat is a complementary food).
And different formats of food:
Wet- Wet cat food is food in cans or pouches, it usually has meat in a gravy or jelly.
Dry- Dry cat food is biscuits or kibbles. You should always give your cat extra water when feeding a dry food.
You might just give your cat just dry food, just wet food or a mix of both!
And even food for different lifestages:
Kitten, adult, pregnant and senior.
Cats are carnivores (meat eaters) so they must have animal protein in their diet. They’re different to dogs so don’t give them dog food.
GIVE YOUR CAT FRESH WATER, NOT MILK
Cow’s milk isn’t good for cats as it’s not very easy for them to digest. So only give them special 'cat milk'. Plus it’s more like a food than drink, so don’t give them too much. But water- they need lots of that so be generous!