A read-only file is a file with the read-only file attribute enabled. It can be opened and viewed like any other file, but writing to it (saving changes) is not possible. In other words, the file can only be read, not written to.
Recover read-only files and folders in Windows
If a file is marked as read-only, it usually means that it should not be modified or that great care should be taken before making any changes.
Things other than files can also be read-only, such as specially configured flash drives and other solid state storage devices such as SD cards. Certain areas of your computer's memory can also be set as read-only.
Aside from the rare situation where you or someone else manually set a read-only flag for a file, most of these types of files are important files that your operating system needs to boot properly. However, if they are modified or deleted, they can cause your computer to crash.
