To develop a hierarchy in classification, we choose the fundamental characteristics among several other characteristics. This fundamental or basic characteristic helps to make the broad division. Then we should pick up next set of characteristics for making subgroups. For example, nature of cell and form of the body is considered to classify organisms into broad divisions (e.g., Prokaryotes and Eukaryotesd). The characteristics of the next level should be dependent on the previous one that will decide the subsequent divisions of the groups.

This process must continue and each time new characteristics should be used.