JavaScript is a powerful and flexible programming language widely used in web development. It allows developers to create interactive and dynamic content, such as animations, form validations, and real-time updates, enriching the user experience. JavaScript runs on the client side, meaning it executes in the user's browser, enabling quick responses to user actions without the need to reload the page. It also supports various frameworks and libraries, such as React and Vue.js, which streamline development and enhance functionality. Overall, JavaScript is essential for building modern, engaging web applications and enhancing website interactivity.