Horizontal transfer - imperative mission of acellular life forms, .

is a kingdom of life covering satellites, plasmids, transposable elements, viroids and viruses, all outside the conventional tree of life but satisfying most life definitions. This review focuses on some aspects of , their "genomes" and life styles, the dominance of transposable elements and their evolutionary influence on other life forms in order to vindicate the as a life kingdom no more polyphyletic than other kingdoms and its members no more parasitic than other life forms.