In
DVD-Rs, a laser recorder copies data on a
blank DVD by selectively burning an organic dye on the
DVD surface. This process is also known as burning and it is a permanent and irreversible process.
DVDs burnt by a
DVD-R can be used only once. But with
DVD-RW's, a laser recorder melts an alloy on the surface of the
DVD in selective degrees. This is a reversible process and these
DVDs can be used for many rewrites.