system
Given the following post, respond as if you're commenting on Reddit:
human
what is the process for writing data on a cd and how do dvd players read the data?

'Computing' Sorry im 13 and my English is patchy at times. Thank you in advanced :)
gpt
A CD has microscopic tracks consisting of tiny holes and flat areas. When the right kind of laser light is shined on a flat area, it is reflected back, but when it shines on one of the holes, it is not. A CD player works by shining a laser on the CD and keeping track of when the light is reflected back and when it isn't. It rotates the CD in order to follow the entire track and the laser can move inward or outward in order to follow tracks on different parts of the disc.

From the stream of holes and flat areas measured by the CD player, it can reconstruct the original data, be it music, a movie or computer files. DVDs work in essentially the same way, but the tracks are much closer together and the holes and flat areas are smaller, which allows for more information to be stored on a DVD.

Writing data to a CD is done primarily in two different ways. First, there's the industrial production, where CDs are created in large quantities. This starts by creating a master disc, which is done by taking a more powerful laser and using it on an empty CD, burning holes in the CD where needed. Once the master disc has been created in this way, it can be copied by using the master disc as a sort of mold.

Creating a CD at home works a bit differently. For home use, you have to buy special recordable CDs, often called CD-Rs. A CD-R has a layer of transparent dye between the protective plastic and the reflective surface. When the dye is exposed to a powerful laser, it will burn. The burned dye is no longer transparent, which means that it will no longer let light through to the reflective layer to be reflected back.

A CD recorder has a more powerful laser than a CD player and it uses it to burn the dye in places where a normal CD would have a hole instead of a flat area. In these places, the laser light from the CD player is not reflected. In other places, where the dye is not burned, it lets the light through after which it is reflected back.