Cats will actually groom in a particular order. If you have you ever watched your cat grooming, you may notice they always start with the head end, so they will wash their paws, to then wash their face and then systematically work through their body before finishing with their tail. …They have hooked barbs on their tongues and this is really helpful to help them
keep their coats clean, it stimulates natural oil production which in turn helps with waterproofing and insulation and also helps to remove the dead fur from their coat. …Some cats will clean and groom each other and this is known as a allogrooming and they tend to do this if they perceive themselves to be in the social group. As well as reinforcing social bonds mutual grooming is really useful to get those hard to reach areas, such as behind the ears.