The history of compact Disc is not very long. The Compact Discs were first introduced in the early 1980s. It's one of the storage media like LP, cassette, floppy disc with more storage space, more compact feature. It makes our life easier for use, but it is a patented technology by Philip and SONY, so it is not a international standard- ISO product, who make the media or the reader need to pay a good amount of money to these two companies. Today we can find CDs everywhere in the world.
People can use CDs to hold music, a lot of information or computer software.
A CD is a simple piece of plastic about 1.2 millimeters thick. It has a single spiral track of data circling from the inside of the disk to the outside. The data stored on the disc can be read by the laser head. Most of the CD consists of an injection-molded piece of clear polycarbonate plastic. During manufacturing this plastic is impressed with microscopic bumps arranged as a single, continuous, extremely long spiral track of data.