Viruses can be classified according to the host cell they infect: animal viruses, plant viruses, fungal viruses, and bacteriophages (viruses infecting bacterium, which include the most complex viruses).
Os virus poden ser clasificados segundo a célula hóspede á que infectan en: virus animais, virus de plantas, virus fúnxicos, e bacteriófagos (virus que infectan bacterias, entre os que están os virus máis complexos).