A form of metahumanity that differs from baseline humans in that they have been augmented through the use of cybernetics, genetic manipulation, mutation, magic, or some other means. They are commonly considered, feared to be, or believe themselves to be the next stage in human evolution, albeit often from a artificial technological adaptation rather than random genetic chance.
Posthumans are only those metahumans which either via some act or via relation to a progenitor's act became something more-than-human. A person who has their genetic code rewritten to become a superman of sorts is a posthuman; this person's children would also be posthuman if they retain the augmentation involved. Those metahumans who are naturally more-than-human, such as the multiple species of Elves, are not posthumans unless they are the result of direct genetic manipulation.
One World Nation
The nation of One World Nation has been 100% Posthuman since its founding and because of this considers itself to be the homeland of all Posthumans in the universe. More information can be found on One World Nation's nation page.