This document provides guidance on aspects of the design of human-system interaction, including: conceptual design, user-system interaction design, user interface design, and navigation design for interactive systems. This document applies to all design and development approaches and methodologies (including: human-centred design, object-oriented, waterfall, HFI (human factors integration), agile and rapid development). This document refers to applicable international standards, where available, rather than duplicating their content. It also provides guidance that is not available in other international standards.