A CD burner, more formally a CD-R drive, is a device used to write data to a recordable compact disc. Though initially sold for hundreds of dollars when they were introduced in the mid-90s, used models can now be found quite inexpensively. These devices arguably helped kickstart the era of music and gaming piracy as one of the first applications was cheaply copying music and game CDs.
CDs hold slightly under 700 MB of data, which works out to about 11 hours of compressed music or a few hours of medium-quality video. The burning process takes anywhere between a few minutes and half an hour, depending on the speed of the CD burner. Devices that encode data to higher-capacity DVD discs are called DVD burners. The name derives from the use of a laser to write data to the optical disc. Lasers are thought to be hot — though the laser used to write CDs is not — hence the term "burning".
There are two types of writable CDs — CDs that can only be written to one time (CD-R), and CDs that can be written and rewritten multiple times (CD-RW). Rewritable discs are rated for up to 1,000 rewrites. On a CD-R disc, an organic dye is used to encode data, and a laser applied to precise points changes the chemical properties of the dye, modifying its reflectivity, which allows a passive laser to read data from the disc in the future. With a CD-R, the CD burning process is permanent and cannot be reversed. On a CD-RW, a crystalline metal alloy is used that can repeatedly transform between a reflective and amorphous state, depending on the amount of laser power applied.
The speed of a CD burner is rated in multiples of 150 KiB/s (kilobytes per second written). A 300 KiB/s burner is rated at 2X, a 600 KiB/s one at 4X, and so on. The fastest possible burners operate at 52X, which causes the disc to rotate about 10,000 times per minute. If the disc moved faster than this, the plastic at the center of the disc would start creeping towards the edges.