UI and UX are essential aspects of technology products, with UI focusing on visual design and interaction, while UX emphasizes the overall user experience. Key principles include user-centered design, consistency, simplification, visual hierarchy, and feedback, which all contribute to effective UI/UX. Popular tools for designers include Sketch, Figma, Adobe XD, and InVision, reflecting the increasing demand for skilled UI/UX professionals in today's tech-driven market.