Originally termed Alternative Humanity Personal Identity (AHPI), alterhuman functions as an umbrella term which covers a broad spectrum of other terms and groups; it most often includes otherkin, therian, fictionkin, plural systems, otherhearted individuals, and otherlinkers, but it may also be used to refer to transhumanists, trans-species individuals, furries, daemians, and vampires among others.

Alters may have different ages, for instance much younger or older; a different gender to the physical body; different names, or no name; different roles or functions, either related to daily life or to trauma; different attitudes, and preferences, e.g, in food, or dress