Similar to how you used the special convention file loading.js in the previous lesson to see loaders, you can use error.js in exactly the same way. When you define an error.js file in a route segment, Next.js automatically wraps that segment and its nested children in a React Error Boundary (Similar to React Suspense Boundary for loading states). This means that if an error occurs within that segment, it will be caught, and a fallback UI (the component exported from error.js) will be displayed instead of the default error page. The only difference is this error.js file has to be a client component. Why? Because the error.js file is meant to catch errors that happen while your app is rendering, and Error Boundaries handle issues during rendering, lifecycle methods, and constructors of child components—they need to be client components to work properly.