Tell about React reconciliation.

React reconciliation is the process of comparing the new virtual DOM with the previous one to determine the minimal changes needed to update the real DOM and refresh the interface.

Key points:

• React creates a virtual representation of the UI (Virtual DOM).
• When the state changes, a new Virtual DOM is created.
• React compares the new Virtual DOM with the previous one (diffing).
• It finds the minimal set of changes (patches).
• These changes are applied to the real DOM, efficiently updating the UI.

Example:

function Counter() {
  const [count, setCount] = React.useState(0);
  return <button onClick={() => setCount(count + 1)}>Clicked {count} times</button>;
}

Each time you click, React creates a new Virtual DOM for the button, compares it with the previous one, and updates only the text inside the button, without re-rendering the entire element.