The DVD-R(Recordable) can only be written once and corresponds in the 2nd version to the types DVD-5 and DVD-10 with 4.7 GB and 9.4 GB storage capacity respectively. During the storage process in a DVD burner, the laser heats the storage layer and changes the substrate, causing it to undergo a reflection change during reading. Data can be stored on the DVD-R in various write modes.
To limit abuse against unauthorized copying, there are two different DVD-R versions, one is labeled DVD-R(A), which stands for Authoring and denotes professional use. These DVDs are written with a laser with a wavelength of 635 nm, have copy protection and are suitable as masters for large-scale production. The second variant DVD-R(G), for general, is written with a laser with a wavelength of 650 nm. The respective blanks can therefore only be written in the DVD recorder with the corresponding laser. There is no difference between the two media types when it comes to reading, which is done with a 650 nm laser on both DVDs.
The DVD Forum has specified a double-layer format for DVD-R burning with phase-change technology. The write speeds for burning are 12x and 16x. The specifications for DVD-R are described in the DVD Book "D".