JavaScript is a versatile and widely used programming language that runs on the client side of web browsers. It provides dynamic and interactive functionality to websites, allowing for actions like form validation, content manipulation, and user interactivity. JavaScript is a high-level, interpreted language known for its flexibility and simplicity, making it accessible to developers of all levels. It plays a vital role in modern web development, powering various frameworks and libraries such as React, Angular, and Vue.js. With JavaScript, developers can create dynamic web pages, build web applications, and handle server-side tasks through frameworks like Node.js.