Props drilling refers to the process of passing props from a parent component to a nested child component through multiple levels of components in the component tree. When a prop value has to be retrieved by a deeply nested component that is not directly related to the parent component, this can occur.

Props drilling can sometimes lead to code that is difficult to maintain and can create unnecessary dependencies between components. It can be mitigated by using alternative approaches such as context or state management libraries like Redux.

Here's an example to illustrate props drilling:

// ParentComponent.js
import React from 'react';
import ChildComponent from './ChildComponent';

const ParentComponent = () => {
  const message = 'Hello from Parent';

  return (
    <div>
      <ChildComponent message={message} />
    </div>
  );
};

export default ParentComponent;

// ChildComponent.js
import React from 'react';
import GrandchildComponent from './GrandchildComponent';

const ChildComponent = ({ message }) => {
  return (
    <div>
      <GrandchildComponent message={message} />
    </div>
  );
};

export default ChildComponent;

// GrandchildComponent.js
import React from 'react';

const GrandchildComponent = ({ message }) => {
  return (
    <div>
      <p>{message}</p>
    </div>
  );
};

export default GrandchildComponent;

In the above example, ParentComponent passes the message prop down to ChildComponent, which in turn passes it down to GrandchildComponent. The message of the prop is accessed by GrandchildComponent through prop drilling.

While props drilling is a simple way to pass data between components, it can become cumbersome when the component hierarchy grows larger. In such cases, alternative solutions like context or state management libraries can provide a more efficient and scalable approach.