Dual-booting is a setup that allows a computer to run two different operating systems, such as Windows and Linux, on the same machine. When the computer starts, users can choose which operating system to load, enabling them to access features and applications specific to each system. This method is useful for users who need to use software that is only available on one operating system or for those who want to explore different environments without needing separate devices. Proper partitioning of the hard drive is essential to ensure both operating systems can coexist without interfering with each other.