What you do for Computer formating?

Basically when formatting a PC you are deleting your operating system. and erasing all the hard drive and installing new fresh copy of Windows . Its used to get rid of some viruses that cant be resolved by Anti viruses and some spywares too. Note !! All data MUST! Be backed up before the process of formating because when u format all ur date will be deleted. you can Store ur data in different hard drive . or in different partition if u have one hdd devide in 2 Such as (Local Disk C: or D:) or in some disks to prevent data loss.
Formatting on a computer means to erase all sort of data from the drive (it can be usb also).

when formatting refer to Windows it means deleting Windows can providing the fresh copy of Windows .during formatting all the install software's will be removed. In short you are deleting everything on your computers hard drive, including the operating system.