What is a usability issue?A usability issue can be defined as a problem that delays or prevents a user from performing a certain task on a product (software, hardware, website) and forces the user to contact other resources (people, manuals, help) to complete the task. A usability issue can potentially cause a user to reject the product and look for alternatives. Finding and solving a usability problem is the goal of all usability efforts by a product development organization. There are a multitude of methods for evaluating the usability of a product, but all methods focus on problem detection and do not go far enough to handle categorization and prioritization. A large part of usability costs are not associated with research but with problem solving, therefore the categorization and assignment of severity levels to usability problems must be robust, reliable and justify the associated cost to solving usability problems (Hertzum, 2006). Categorization and prioritization have traditionally lacked scientific interest and have been studied mainly in the context of comparing assessment methods (Hassenzahl, 2000). This article will focus on the existing literature on usability problem categorization, present a critical analysis of the methods and also highlight their areas of positive influence. The article will then present a practitioner's perspective on categorization and lead to a conclusion. Existing literature on usability problem categorization This section of the article reviews some existing approaches to usability problem categorization. Detailed scales and ranges for each of the approaches discussed below are provided in the appendix for your reference. Rubin and Chisnell's modelRubin and Chisnell (...... middle of article ......ign. INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION, 21(2), 125-146. Keenan, SL, Hartson, HR, Kafura, DG and Schulma, RS (1999). The Taxonomy of Usability Problems: A Framework for Classification and Empirical Analysis, 4(1), 71-104.Molich, R., Jeffries, R. and Dumas, J. S. (2007). Making usability recommendations useful and usable. Journal of Usability Studies, 2(4), 162-179.Nielsen, J. (1995). Usability Problem Severity Ratings: Article by Jakob Nielsen retrieved February 7, 2014 from http://www.nngroup.com/articles/how-to-rate-the-severity-of-usability-problems/Nielsen, J (2006). Usability issue severity ratings. Useit.com, 4–5. Rubin, J. and Chisnell, D. (2008). Usability Testing Handbook (2nd ed.). C. (1999). Usability interface: severity scales. User-friendly interface, 5(4).