JavaScript is a programming language that's widely used to create interactive effects within web browsers. It's a key technology for web development, alongside HTML and CSS. JavaScript allows developers to build dynamic websites, handle events (like button clicks), manipulate webpage content, and communicate with servers. It's versatile and can be used on both the client side (in the browser) and the server side (with environments like Node.js). As ahigh-level, interpreted programming language, JS is used to build and enhance interactive elements on web pages. It allows developers to manipulate web content, respond to user actions, and communicate with servers in real-time. Initially designed for client-side scripting, JavaScript has expanded to support server-side development through frameworks like Node.js, making it a comprehensive tool for an array of applications, from dynamic websites to mobile apps and server-side services.