Catkin (or felinekin) are a type of therian. They identify as some sort of feline (including big cats, domestic cats, extinct felines, etc.), making this a broad and diverse group. Catkin, like the majority of 'kin, may experience things such as phantom limbs and mental shifts related to their kintype, including the feeling of ears moving towards loud or interesting noises. Some felines would rather identify as were-cats (deriving from the name were-wolf), though this term has lost popularity since the term "catkin" was established in the community.
It's common that Catkin/FelineKin like to dress in a way that expresses how the spiritually/mentally feel. Many online stores such as storenvy and etsy sell a lot of cat-themed clothing/accessories that are great for catkin to express themselves.