Definition:
A Dual-Layer DVD differs from from a standard DVD by employing a second physical layer within the disc itself. A drive with dual layer capability accesses the second layer by shining the laser through the first semi-transparent layer.
Dual layer recording is available on DVD-R and DVD+R discs for storing significantly more data, up to 8.5 GB per disc, compared with 4.7 GB for single-layer discs.
