Cat owners often see cats rubbing their heads against themselves. This is actually a behavior of cats expressing love to their owners. For mammals, if they rub their heads against something, they are expressing their feelings. For cats, rubbing their heads on things also has a sense of occupying territory. They want to leave their own scent.

Cats leave their own scent, not only to declare their sovereignty. You can also tell other cats that you exist, like you can find me here.

Cats rub their heads against you without hesitation and are eager to leave their own scent, which means they trust you very much. For cats, they like their family members to smell like them, so they do their best to leave their own scent behind.