Usability refers to making websites easy to use without training. Key factors include ease of learning, efficiency, reducing errors, and satisfaction. User experience considers how users feel about a product or service and their level of satisfaction. Usability ensures users can accomplish tasks, while user experience aims to make the experience as delightful as possible. Some principles for good usability and user experience include making important information obvious, reducing unnecessary choices, using whitespace for structure, and eliminating potential confusions.