DVD-5: a single-sided and single-layer disc which holds 4.7 GB of data.
DVD-9: a single-sided and double-layers disc with capacity of 8.5 GB.
DVD-7: a double-sided and single-layer disc with capacity of 9.4 GB.
DVD-18: a double-sided and double-layers disc holds 17 GB.
Blu-Ray: a single layer disc holds 25 GB and a dual-layer disc holds 50 GB.