DVDRW's (Rewritable) Media
DVD rewritable disks come in 2 formats, DVD-RW & DVD+RW.
Both when burned will do the same job but originally they were 2 different formats owned by different alliances of companies. Initially users had to buy a DVD+R dvd burner OR a DVD-RW burner. In the last few years though all DVD burners accept both the DVD+RW & DVD-RW formats.
Only some standalone DVD recorders now only accept one format so be careful if buying and check the manual before purchasing.
DVD rewritables do the same job as standard DVD media at storing movies, data, music and images etc but with the added functionality of being able to delete and use them again and again. Standard DVD can only be written to once then the data cannot be altered in any way.
The capacity of a DVD Rewritable is 120mins / 4.7GB.