Virtual DOM:

• Imagine a lightweight, in-memory copy of the actual DOM tree in your React application. This is the virtual DOM.

• It's a JavaScript representation of the UI, reflecting the current state of your components.

• React keeps this virtual DOM up-to-date whenever there's a change in your application's state.

Reconciliation:

• This is the process where React compares the previous virtual DOM with the new one created after a state change.

• Reconciliation involves a clever diffing algorithm that efficiently identifies the minimal changes required in the real DOM.

• This avoids the cost of blindly re-rendering the entire DOM for every state update, leading to smoother performance.

Fiber:

• Introduced in React 16, Fiber is a new reconciliation engine that significantly improves performance, especially for complex UIs with a lot of animations or interactions.

• Unlike the previous reconciliation approach, Fiber allows for:

  • Incremental rendering: React can break down the rendering work into smaller chunks and spread it out over multiple browser frames, resulting in smoother animations.

  • Priority scheduling: React can prioritize urgent updates (like user interactions) over lower priority ones, ensuring a more responsive user experience.

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github.com/acdlite/react-fiber-architecture