React is a JavaScript library for building user interfaces using a component-based architecture. React manages UI state through declarative rendering and efficiently updates the DOM using a virtual DOM diffing algorithm. It is widely used for single-page applications, mobile apps (via React Native), and interactive dashboards.
Why it matters
React simplifies building complex UIs by breaking them into reusable components. It improves maintainability, performance, and developer productivity. Its ecosystem includes powerful tools like hooks, context, and server-side rendering.
Examples
Building a form component, using hooks to manage state, or rendering lists from an API. Lessons like React-related deep dives in Track 7 reinforce UI patterns.