Write protection is a setting or physical switch that makes a USB storage device, such as a flash drive or memory card, read only. When write protection is active, files already on the device can be read and copied, but nothing new can be written, and existing files cannot be changed or deleted.
Some flash drives and SD cards include a physical write protection switch on the device itself, while other devices rely on software controls, either from the operating system or from utilities that lock a drive at the file system level. Write protection is useful for distributing files safely or protecting important data from accidental changes.
It can also serve as a defence against certain kinds of malware that try to write themselves onto removable storage, since a genuinely write protected drive simply refuses any such write attempt. See our USB security guide for more on protecting data on removable storage.
