What is JSX and why does React use it?

JSX stands for **JavaScript XML**. It is a syntax extension for JavaScript that looks similar to HTML or XML and is used primarily with React to describe what the UI should look like. Instead of using plain JavaScript function calls to create UI elements, JSX allows developers to write code that visually resembles HTML, making the code more readable and easier to understand. React uses JSX because it provides a concise and expressive way to define the structure of a component’s output. Under the hood, JSX is not valid JavaScript by itself. During the build process, tools like Babel transform JSX into regular JavaScript function calls — specifically, calls to `React.createElement()`. For example, a JSX snippet like: ```jsx const element = Hello, world!; ``` is transformed into: ```js const element = React.createElement('h1', null, 'Hello, world!'); ``` This means **JSX is not required** to use React; you can write React components using plain JavaScript by calling `React.createElement()` directly. However, JSX is widely used because it simplifies the syntax and makes the code more declarative and easier to maintain. In summary: - **JSX is a syntax extension for JavaScript that looks like HTML.** - **It is used in React to describe UI elements in a more readable way.** - **JSX is compiled into `React.createElement()` calls behind the scenes.** - **Using JSX is optional but highly recommended because it makes React code more expressive and easier to write.**