Write-protection is the ability of a hardware device or software program to prevent new information from being written or old information being changed. Typically, this means you can read the data, but not write. In the picture is an example of a write-protect switch on an SD card that turns on and off write-protect on that card.
Enable and disable write-protection using software
To protect a file in the Microsoft Windows command line or MS-DOS, use the attrib command. With Windows, you can view the file properties and enable the read-only attribute. Finally, with a Linux variant or Unix, the chmod command could be used to enable and disable write-protection.
Tip: With the Microsoft Windows attrib command and file properties suggestion this allows you (and anyone else) to add and remove write-protection (read-only). If you want to prevent others from changing the write-protection, setup network users and permissions.
Enable and disable write-protection with hardware
Earlier removable media such as a floppy diskette use write-protect to protect a disk from being erased or overwritten. The 5.25-inch floppy diskette had a hole in the upper corner of the diskette that could be covered with tape to enable write-protection. The 3.5-inch disk had a tab in the corner that could be moved up or down to enable or disable write-protect. By moving the tab to block the hole or unblock the hole, you could enable and disable write-protection.
Why use write-protection?
As mentioned above, by using write-protection it helps prevent data from being accidentally overwritten or erased. For example, if you had an SD card with lots of pictures you didn't want accidentally deleted you could enable write-protection. Of course, if you were to do this, no new pictures could be added until write-protection was removed.
With floppy disk companies would often have the diskettes write-protected to prevent the diskettes from being mistakenly overwritten and erasing the program on the diskette. With 3.25" floppy diskettes, the tab would often be missing from the diskette. However, covering the hole with a piece of tape would allow you to write to the diskette.
Should I use "write protect" or "write-protect" in my writing?
When writing "write-protect," "write-protected," or "write-protection," you should always hyphenate the two words.