A factory reset is a process that restores a device, such as a smartphone or computer, to its original settings as if it were new. This means all personal data, apps, and custom settings are erased, allowing the device to function like it did when first purchased. This process is often used to troubleshoot issues, improve performance, or prepare a device for sale. It is important to back up any important data before performing a factory reset, as all information will be permanently deleted from the device, including files, photos, and contacts.