Why Do Cats Rub Up Against Everything - Including Me?!
Cats have scent glands on their lips, chins, and tails. Additionally, scent glands are present on each side of their heads, and between their front paws. They use these glands to mark their territory with their scent.
When your cat rubs you, she is marking you with her scent, thus claiming you as "hers". In the process of doing so, she picks up your scent as well. Cats rub up against furniture and doorways as well - to mark the objects and places as "hers".