The establishment of a hierarchical system of categories on the basis of innate natural relationships among organisms is called classification.
Taxonomy is the science of biological classification.
Phenetic classification:
Itis an attempt to classify organisms according to the overall similarity of existing organisms, usually in morphology or other available characteristics.
For example, lizards, crocodiles, and turtles are seen as scaly tetrapods and they are placed under the same class of Reptilia.