JavaScript is a versatile, high-level programming language primarily used for web development. It enables dynamic and interactive content on webpages, handling client-side scripts for behavior, and facilitating communication with servers via AJAX. JavaScript runs in web browsers, allowing manipulation of HTML and CSS, enhancing user experience. Its event-driven architecture supports asynchronous programming, essential for handling user input and network requests without blocking the execution of other code. JavaScript’s ecosystem is rich with frameworks and libraries like React, Angular, and Vue.js, empowering developers to create modern web applications efficiently. Its ubiquity and flexibility make JavaScript indispensable for both front-end and back-end web development.