Why was DVD so Revolutionary

DVD initially stood for Digital Video Disc 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 the following table:

Feature
DVD CD-ROM
Substrate diameter / thickness (mm)
120 / 1.2 120 / 1.2
Sides
1 or 2 1
Layers per side
1 or 2 1
Capacity (GB)
4.7, 8.54, 9.4, or 17 0.7
Track pitch (microns)
0.74 1.6
Min pit length (microns)
0.4 - 0.44 0.83
Linear velocity used for scan (m/s)
3.5 - 3.84 1.3
Laser wavelength (nm)
635 or 650 780
Numerical aperture
0.6 0.45
Modulation
8 to 16 EFM (8 to 17)
Error correction code (ECC)
RSPC CIRC
Durability and dust/scratch
same as that of CD high

• The main features of the DVD formats can be summarized as follows:
• Backwards compatibility with current CD media (at least the newest models of DVD drives)
• Physical dimensions identical to compact disc with total thickness equal to 1.2 mm, but with capacity at least 7 times larger than that of CD.
• Capacities of 4.7 GB, 8.54 GB, 9.4 GB, and 17.08 GB, depending on the disk structure.
• Single-layer/dual-layer and single/double sided options.
• DVD replication process is similar to that used for compact disks.
• A disc-based format means fast random access like in hard drives and CDs and unlike tapes.
• Designed from the outset for video, audio and multimedia. Meets the requirement for 133 minutes of high quality video on one side of a disk.
• DVD-ROM for enhanced multimedia and games applications.
• DVD-Video for full length high quality movies on one disc.
• DVD-Audio for higher quality music, surround sound and optional video, graphics and other features.
• All formats use a common file system.
• Copy protection built into standard (unless it is broken...)