Hard reset
A hard reset is a process of reverting a device back to the state it was in when shipped from the factory. That is to say, it erases all data including apps, user profiles, and settings. Hard resets can be helpful for wiping all data before selling a computer, smartphone, or tablet. Also, they are useful when you have an operating system error that you cannot fix.
A hard reset should not be confused with a cold boot, also known as a hard boot. Also, this term can describe a factory reset.
Router hard reset
With a network home router, there is a reset button the back of the router that reboots the router when pressed. A hard reset is when you press and hold in on the button for 5-10 seconds and then let go. The hard reset on a router resets all the router settings to factory default settings.
PC or laptop hard reset
A hard reset is performed by reformatting your computer and reinstalling its operating system.
Smartphone hard reset
With a smartphone, a hard reset restores the smartphone back to the original operating system and apps. A hard reset erases all user data and any apps installed by the user.