Many companies are using product platform concepts to gain economies of scale and to identify new market opportunities. Though the area of product platforming continues to be actively investigated by both industry and academia, there is no comprehensive classification scheme that can provide a clear picture of the existing problems and possible future research directions. Hence, in the present paper, we introduce a broad taxonomy that classifies product platform problems based on the product development stages. This can serve as a basis to: (1) Extract and categorize problems from research literature; (2) Identify potential extensions and/or new problems that have not been addressed in the literature; and (3) Identify existing problem sets and/or develop new problem sets for benchmarking purposes. We introduce a Conditions and Assumptions Code (CAC) scheme and use it in the identification of benchmark problems as well as in analyzing two classes of evaluation methods adopted for the platform problems: metrics-based and optimization-based Thus, we have not only categorized existing problems but also identified possible future research problems in each of the categories. This categorization serves as a navigation tool to understand the progress made in this field so far and to identify new research directions.