A hard reset, also known as a factory reset, is a procedure that restores an electronic device to its original factory settings. It erases all data, apps, and settings from the device, returning it to the state it was in when it first left the factory.
Hard resets are often used to troubleshoot problems with a device, such as freezing, crashing, or not responding. They can also be used to remove all personal data from a device before selling or giving it away.