The principles of user-centered design focus on creating products or systems that prioritize the needs, preferences, and limitations of end-users. Key principles include conducting user research to identify user needs, involving users in the design process through prototyping and usability testing, and iterating designs based on user feedback. Additionally, the approach emphasizes creating intuitive and accessible interfaces that enhance the overall user experience. By centering the design process around users, developers can ensure that products are more effective and satisfying to use.