Superhuman can mean an improved human, for example, by genetic modification, cybernetic implants, or as what humans might evolve into, in the distant future. Occasionally, it could mean an otherwise "normal" human with unusual abilities, such as psychic abilities or exceptional proficiency at something, far beyond the norm.
Superhuman can also mean something that isn't human, but considered to be "superior" to humans in some ways. A robot that easily passed the Turing test, and could do some things humans can't, could be considered superhuman. A very intelligent or strong alien could be considered superhuman.
The concept of the superhuman is quite popular in science fiction, where superhumans are often cyborgs, mutants or genetically engineered. The greatest publicity of the concept is, of course, comic book superheroes, such as Superman. The term is often used in discussions of comic book characters because the terms Superman and super hero are registered as trademarks. Superhuman characters in various comics, role-playing games and other entertainment media have also been referred to as metahuman or posthuman.