Cats rub their faces on things for many reasons depending on the context or object being rubbed.
Kitten keeps rubbing face on floor.
When your cat engages in head bunting or head rubbing he is placing his scent there as a social and affectionate gesture.
Lip rubbing is often reserved for marking objects.
Marking is used as a way to keep any potential enemies or rivals away.
Rubbing is a natural feline marking behavior.
If the cat knows you already or is just really enthusiastic about people he may not wait for a polite greeting.
They are covering you and the things around them with pheromones which come from glands on their face and head.
When your cat rubs its head and cheeks on the floor it can be leaving its scent markers on the house and over your feet.
Head butting is an over the top version of face rubbing.
Cat to cat head bunting and allorubbing are reserved for cats who already have a familiar and friendly relationship.
Cats typically display head bunting toward other cats dog companions and humans.
Cats rub on walls furniture shoes and even other things lying around on the floor.