Threeja is a three-dimensional (3D) graphics library that provides a simplified and intuitive interface for creating and rendering 3D graphics in JavaScript. It offers a range of features and functionalities to easily build interactive and visually appealing 3D scenes, including support for lighting, materials, textures, and animations. Threeja simplifies complex tasks like geometry creation, camera positioning, and scene management, making it accessible for both beginners and experienced developers. With its robust capabilities and extensive documentation, Threeja empowers developers to bring their 3D ideas to life in web applications with ease.