A hard reboot, also known as a hard reset, involves forcibly shutting down and restarting your computer, typically by holding down the power button for about 10 seconds until the computer turns off, then pressing it again to turn it back on. This method should be used sparingly, as it bypasses the normal shutdown process and can lead to data loss or corruption, especially if programs are running or files are open. It's most often used when the computer is completely unresponsive, and other restart methods are not working.