What is React? Declarative UI components
React is a JavaScript library for building user interfaces from components. You describe UI as a function of state; React updates the DOM efficiently. Maintained by Meta and a large community, it dominates modern web front ends—often with Next.js for rendering and routing.
In one sentence
React splits the UI into components that update from state.
We have a full page on this subject, with the detail, the use cases and how we approach it.
React