Use of Faceted Classification

Faceted classification is a system of identifying items in multple groups in order to provide the users the ability to find items based on more than one criteria. For example, a user looking for a computer may prefer to browse for products by PC vs. MAC, notebook vs. desktop, brand name, price, or any other element that may distiniguish one subset of computer from another.

Frequency of Faceted Classification: is it used?