JSX stands for JavaScript XML. It is a syntactic extension to JavaScript that allows developers to write HTML-like code inside JavaScript. JSX is primarily used with React, a JavaScript library for building user interfaces.

  JSX provides a way to describe the structure and appearance of UI components in a more declarative and intuitive manner. Instead of manipulating the DOM directly using traditional JavaScript methods, JSX allows developers to write code that closely resembles the final rendered output.

  Here are a few reasons why JSX is used:

  1. Concise and expressive syntax: JSX simplifies the process of creating and maintaining complex UI structures by providing a concise syntax for defining components. The HTML-like syntax makes it easier to visualize the structure of the UI and understand how it will be rendered.

  2. Component-based architecture: React follows a component-based architecture, where UI elements are broken down into reusable building blocks called components. JSX seamlessly integrates with React components, allowing developers to define component hierarchies and pass props between them.

  3. Performance optimizations: JSX is optimized by tools like Babel to efficiently and selectively update only the components that have changed. This is achieved by using a virtual DOM, which is a lightweight copy of the actual DOM. JSX helps in generating the virtual DOM efficiently by representing the UI structure in a simplified and deterministic manner.

  4. JavaScript integration: JSX is an extension to JavaScript, which means that JavaScript code can be directly embedded within JSX expressions. This allows developers to use JavaScript expressions and logic within their JSX code, making it more powerful and flexible.

  In summary, JSX is used to write declarative and component-based UI code in the context of React. It enhances code readability, maintainability, and performance by providing a concise syntax closely resembling the expected UI output.