PreloadJS is a JavaScript library designed to simplify the process of loading assets like images, audio, and video files in web applications. It provides a straightforward API that allows developers to manage the loading of multiple files efficiently, ensuring that all necessary resources are available before the application starts. By using PreloadJS, developers can track the progress of asset loading and handle errors gracefully. This enhances the user experience by preventing incomplete or broken content from being displayed. Overall, PreloadJS is a valuable tool for anyone looking to create smooth and responsive web applications.