Applying different CSS classes based on component state or props is essential for creating dynamic and interactive user interfaces in React applications. As the creator of CoreUI, a widely used open-source UI library, and with over 25 years of experience in software development, I’ve implemented countless components that require conditional styling based on user interactions and data states. The most effective approach is using template literals with conditional logic, which provides clean, readable code for simple conditions. For complex conditional class logic, the classnames library offers superior maintainability and readability.