This document discusses design principles and usability, including Gestalt principles of visual organization, using a grid system to place elements, applying principles of eye flow, and tips for usable buttons, text alignment, color, and white space. The key Gestalt principles defined are proximity, similarity, continuity, and closure. Elements placed on a grid help group information and relax eye flow compared to elements not on a grid. Users typically look first at large, irregular, dark elements in the center. Buttons should clearly express their function through affordance. Text alignment should create a visual line for accessibility. Color schemes should be simple and consider color blindness. White space allows the user to focus on content.