React 18 enhances error handling, preventing app crashes by catching and managing errors in child components.
An error boundary component captures errors from its children, updating the state on error using getDerivedStateFromError and componentDidCatch logs the errors.

Here are 10 key improvements:

1. Concurrent Mode: The latest version of React introduces Concurrent Mode, streamlining UI responsiveness by breaking large updates into smaller, prioritized pieces, with the ability to pause and resume updates, preventing main thread blockage.

2. Suspense: It's awesome because it lets your components hold off on rendering until they've fetched all the data they need. This means you can make your app look way better while it's loading stuff, instead of just showing a boring blank screen or a spinner.

3. Server Components: They're a special kind of component that you can render on the server and then send over to the client as HTML. It's like giving your app a speed boost, especially for folks visiting for the first time without a cached version of your site.

4. Automatic Batching: In older versions of the library, you had to manually group updates together to keep your app running smoothly. But in this latest release, this grouping happens automatically. That means you can update multiple things at once without having to do any extra work to optimize performance.

5. Improved Profiling: This version of React has better profiling tools, making it simpler to analyze and optimize your app's performance. These new tools let you track how long each component takes to render, helping you spot any performance issues.

6. Improved Accessibility: In this iteration, there are updates that enhance accessibility, catering better to users with disabilities. One notable addition is the focus-visible attribute, aiding keyboard users in identifying which element is currently in focus.

7. New APIs: For instance, the useTransition hook enables creating animations based on user actions. Similarly, the useDeferredValue hook helps delay processing costly computations.

8. Improved Hydration: The latest version boosts hydration, the method of rendering server-generated HTML on the client. The updated process is quicker and more effective, enhancing your app's performance.

9. Improved Error Handling: This release enhances error handling, simplifying debugging and issue resolution. The updated error boundary API enables you to capture and manage errors within individual components, preventing them from causing app-wide crashes.

10. Improved Developer Experience: This version boosts developer experience with features like “startTransition” API for deferred rendering after state updates, easing asynchronous code writing. Also, the “component stack traces” offer detailed error information, aiding quick issue identification and resolution.