Final answer:
To back up files on the same DVD multiple times, use a DVD-RW, which allows erasing and rewriting data. DVDs store digital information in the form of pits and lands created by a laser, offering large information-storage capacity.
Step-by-step explanation:
For backing up files on the same DVD repeatedly, the best type of DVD to use is a DVD-RW (DVD ReWritable). Unlike DVD-R (recordable), which can only be written once, a DVD-RW allows for data to be erased and rewritten multiple times. When considering the information-storage capacity and the need for multiple backups, the rewritable feature of DVD-RW is crucial.
Traditional music CDs and DVDs store information in the form of pits and lands created by a laser on the disc's surface. As per Figure 30.40, these pits are read by the reflection of a laser beam, which can decipher the digital information based on how the beam scatters. This technology allows for a large amount of data to be stored and accessed, which is significantly greater than that of older storage media like vinyl records and cassette tapes.