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How is data recorded on a CDROM? How is it read?

CD-ROM (an abbreviation of "Compact Disc read-only memory") is a Compact Disc
 that contains data accessible by a computer. While the Compact Disc format was originally
 designed for music storage and playback, the format was later adapted to hold any form of
 binary data. CD-ROMs are popularly used to distribute computer software, including games
 and multimedia applications, though any data can be stored (up to the capacity limit of a
 disc). Some CDs hold both computer data and audio with the latter capable of being played
 on a CD player, whilst data (such as software or digital video) is only usable on a computer.
 These are called Enhanced CDs. Data is stored on the disc as a series of microscopic
 indentations ("pits", with the gaps between them referred to as "lands"). A laser is shone
 onto the reflective surface of the disc to read the pattern of pits and lands. Because the depth
 of the pits is approximately one-quarter to one-sixth of the wavelength of the laser light used
 to read the disc, the reflected beam's phase is shifted in relation to the incoming beam,
 causing destructive interference and reducing the reflected beam's intensity. This pattern of
 changing intensity of the reflected beam is converted into binary data.

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