The face-butt is more than eliciting petting; felines in the wild often face-butt as a "hello" to those in the pride they are close to. There are five or more scent glands on a cat's head. They are secretly smearing and sharing this scent on you. read more
Petting a cat is akin to grooming it. They enjoy the sensation if you're doing it properly. Since we are their personal servants, they will sometimes demand we serve them. read more
Note though, that modern feral cats, such as are often found on farms, generally do not like being petted. So far as I know, feral cats are not genetically different from housecats, so there is undoubtedly an environmental component to cats’ attitude towards being petting. read more