What is a read-only file or folder?

A read-only file is protected from accidental deletion and changes to its content. To change a file to read-only, right-click the file, and then click Properties. In the Properties dialog box, click the General tab, and then select the Read-only check box. To make changes to a read-only file, clear the Read-only check box, or save the file with a different name.

Picture of the Read-only check box in the Properties dialog box
The Read-only check box in the Properties dialog box