Justify at what extent the phylogenetic relationship is useful as a criterion for classification?

Phylogeny is the evolutionary history of an organism. It shows the true kinship of organism.
Such relationships are not clear in all cases. Only fossil record can provide such relationships, but complete records are not available for such studies. Hence, the phylogenetic relationships are ascertained from morphology, cytology, genetics, physiology and biochemistry for the correct classification of the-oiganisms.