The "R" in DVD-R stands for "recordable," indicating that data can be written to this form of optical disc. Much like their older counterpart, the CD-R, DVD-Rs use colored dye and lasers to accomplish what printing does for normal DVDs. DVD-Rs also have the same data degradation over time problems that CD-Rs have, especially when exposed to ultraviolet light. However, they can hold significantly more data: anywhere between 4-5 gigabytes is a common upper limit on DVD-R capacity, as compared to the 650-700 megabytes for CD-Rs. Note that DVD-R is not to be confused with DVD+R, as they are mutually incompatible standard formats. DVD-Rs can also be dual-layer, allowing approximately twice the data to be written to a single disc with only a minor delay in accessing the data as a side effect.
Apple iPhone will finally multitask with OS 4.0