Viruses were classically named after the very same Latin word virus, originally meaning poison or venom. Public understanding of viruses reinforces their “malign” aspects, especially nowadays under the COVID-19 global pandemic. It is our aim here to propose a new way to view viruses and understand their origins and evolution. First, viruses are the most abundant biological systems found on Earth. They can be found almost everywhere and form a subtle biological layer named virosphere. Second, viruses are probably the most important drivers of molecular evolution and they are active agents of ecosystems maintenance and homeostasis, allowing and driving their dynamic modification. A significant number of eukaryotic genomes are composed by genome elements similar to viruses and these endogenous viruses are continuously acting for our equilibrium and fitness. They are responsible for the origin of species-specific orphan genes that allow adaptation through the development of specific traits in separate lineages of eukaryotes. Accumulated evidence indicate that a viral infection was responsible to create the eukaryotic nucleus and, also, it is a syncytium structure caused by viral replication that allows the formation of the placenta. Therefore, viruses were fundamental for the evolutionary fate of eukaryotes and mammals. The presence of virus-specific genes that are absent in cellular organisms indicates that viruses existed before cells. Besides, such as progenotes, viruses are simply ribonucleoproteic entities and their capsids are orders of magnitude simpler than proteolipidic membranes. Here, we (i) propose a complete scenario to describe the major transitions in prebiotic evolution, (ii) present the possibility that viruses emerged before LUCA, and (iii) suggest that viruses originated at the age of progenotes. However, viruses do not form a monophyletic clade. They should be seen as an evolutionary stable strategy recurrently achieved by biological systems to survive. We propose that the word “VIRUS”, known as venom, is historically mistaken and introduce a new interpretation for their name as an acronym for “Very Important Replicator Unit and Symbiont”. But more than being “very important”, viruses are of “Utmost” relevance for the maintenance of life in biosphere, by which reason we suggest referring to them as “UIRUS” to reinforce their incredible role in symbiosis and their beneficial characteristics over the infectious ones.