The common definition for taxonomy comes from the biological sciences and refers to the organization into groups of members that share similar characteristics. In this case, the members are chart types and the shared characteristic is based on the primary data portrayal function.
Selecting the appropriate visualization method will be influenced by the definition work you undertook earlier in the methodology to clarify the intention of your visualization communication.
It is about starting the journey towards identifying the most suitable way to answer your main data questions: how are you going to show, what it is you want to say.
Here is an outline of the primary communication purpose of each method classification: