Setting your important or personal files to read-only can help protect them from unintentional or unauthorized changes. When a file is set to read-only, it can't be changed.
Right-click the file that you want to set to read-only, and then click Properties.
Click the General tab, select the Read-only check box, and then click OK.
If you need to make changes to the file later, you can turn off the read-only setting by clearing the Read-only check box.
In the same way that you set a file to read-only, you can set a folder to read-only. However, it doesn't affect the folder itself. Setting a folder to read-only makes all the files currently in the folder read-only. Any files that you add to the folder after you set it to read-only won't automatically be read-only files.
Read-only files can't be modified, but they can be copied, moved, renamed, or deleted. It's possible that moving, renaming, or deleting a read-only file can cause a program that relies on the file to stop working properly.