JSX (JavaScript XML) is a syntax extension to JavaScript that allows developers to write HTML-like structures within JavaScript code. It's primarily used with React, a popular JavaScript library for building user interfaces. JSX code is not directly executable by browsers; it needs to be transpiled into standard JavaScript using tools like Babel. This transpilation process converts the JSX elements into regular JavaScript function calls that create the corresponding DOM (Document Object Model) elements. JSX simplifies the process of creating and managing dynamic user interfaces by providing a more declarative and readable syntax for describing the structure of UI components. It enhances code maintainability and readability, especially in complex applications with intricate UI structures. JSX also enables static analysis and type checking, improving code quality and reducing errors during development. While primarily associated with React, JSX can be used with other JavaScript frameworks and libraries as well, provided the necessary transpilation tools are configured.