In React, components are the building blocks of the user interface. They allow you to break down the UI into independent, reusable pieces, each handling its own functionality and rendering.
Key Points:

Types of Components: Functional Components: Simple JavaScript functions that return JSX (React’s syntax for rendering UI). They can use hooks like useState and useEffect. Class Components: Older way of defining components using ES6 classes. They can manage their own state and lifecycle methods.

Example:

Functional Component:

function Greeting() {
  return <h1>Hello, World!</h1>;
}

Class Component:

class Greeting extends React.Component {
  render() {
    return <h1>Hello, World!</h1>;
  }
}

Reusability:

Components can be reused across the app, making it easier to build complex UIs by combining smaller, focused components.

In short, React components encapsulate the logic and UI into reusable pieces.