TAXONOMY

Taxonomy is the practice, process and science of classification.

This could be:

a group - named or numbered - to which items can be assigned to, as a result of similarities or defined criterias.

This is one of the central aspects of research within Graphic Design.

Triangulation: research model based on 3 particular pieces of information or 3 categories.

for example: pens, pen users, and pen colour. These three pieces of information can be processed in order to create graphical solutions.