What is useCallback and why is it used?

useCallback is a React Hook that memoizes a function so that it only gets recreated when one of its dependencies changes.

const memoizedCallback = useCallback(
  () => {
    // function body
  },
  [dependency1, dependency2] // dependencies
);

• memoizedCallback: A function that only updates when dependencies change.
• dependencies: Array of variables that trigger recalculation of the function if they change.

Why is it used?

It's primarily used to optimize performance by preventing unnecessary re-creations of functions, especially when those functions are passed as props to child components that use React.memo.