CDs and DVDs Technology
... DVDs have also dominated the market and successfully replaced the VHS cassette as the number one choice for movies. CDs and DVDs are optical storage media, in other words they hold contents in digital form, which are written and read by a laser. CDs and DVDs are similar in size and shape; the discs have the same diameter, the same thickness, similar shiny surface, and weigh the same. ... CDs can hold a maximum of 650 or 700 MB (Megabytes) of data; on the other hand, the DVD has the capacity to hold at least 4. ... CDs do not have this capability, only DVDs have this added advantage. ... CDs and DVDs are currently available in different formats. ... The DVDs are a little more complicated with many more different formats, which are not necessarily compatible with each other. ... CDs and DVDs are indeed important technological advances. ... CDs cost around $0.20 per disc, while the DVDs cost about $1. ... The low cost of CDs and DVDs has made backing-up a hard-drive more feasible since it would no longer be necessary to purchase an expensive new hard-drive.