Whittaker has given the famous Five- Kingdom Classification. According to this classification the five kingdoms are Kingdom Monera, Protista, Fungi, Plantae and Animalia. These kingdoms are divided on the basis of Number of cells, Cell type, Cell wall, Mode of nutrition and Ecological role. All these are characters of living cell. Viruses did not get any place in this kingdom because these are not considered as 'true living'. Viruses do not have cell organelles and hence do not carry metabolism and cannot exist independently. These characters define them as non living and hence Whittaker did not include them in his Classification.