UNetbootin is a free and open-source software tool that allows users to create bootable USB drives from various operating systems. It supports a wide range of distributions, including Linux and Windows, making it easy to install or try out different OS versions without needing a CD or DVD. The application is user-friendly, featuring a simple interface that guides users through the process of selecting an ISO file and the target USB drive. Once the setup is complete, users can boot their computers from the USB drive, facilitating system recovery, installation, or testing of new operating systems.