DVD initially stood for Digital Video Disk but now stands for Digital Versatile Disc. Like a CD, DVD is an optical storage system for read-only, recordable, and rewritable applications. But, being similar to a CD in many ways, DVD is considered to be a CD future replacement.

The main differences between the CD and DVD are summarized in Table 4-7 and also in Figure 4-17.

Figure 4-17. Comparison of the main features of the CD and DVD discs.

Table 4-7. DVD versus CD-ROM
Substrate diameter/thickness (mm)120/1.2120/1.2
Sides1 or 21
Layers per side1 or 21
Capacity (GB)4.7, 8.54, 9.4, or 17~ 0.7
Track pitch (micrometers)

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