Though there are many specific types of CDs, we shall only cover the whom most commercially available writeable types. They are the CD-R and CD-RW.
CD-R stands for compact disc, recordable. A person can only write once on this CD, though it can be read as many times as wished. It can be played in CD players and CD-ROM drives. In a normal CD, polycarbonate plastic substrate, a thin reflective metal coating, and protective outer coating layers are present. However, in a CD-R, an extra layer is present and is an organic polymer dye lying between the polycarbonate and metal layers and serves as a recording medium. A pregrooved spiral track guides the laser for recording data, which is encoded from the inside to the outside of a CD in a continuous spiral, much like the way it is read. The laser makes that are not dissimilar from the pits and lands of a normal CD. After the encoding process is completed, the data can be read as a normal CD. The CD recorders are sometimes referred to as CD burners. Modern recording devices can also read CDs as well. CD-Rs can be created in any CD-R or CD-RW drive.
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