A CD, or compact disc, works by using a laser to read information on its surface. The disc is made up of a thin layer of aluminum, covered by a layer of plastic, and then a layer of protective lacquer. The aluminum layer contains tiny pits and lands that represent the 0s and 1s of digital information. When the laser shines onto the disc, it reflects off the pits and lands differently, which is read by the CD player and converted into sound.
A CD stores music digitally, while a record stores music in analog form. This means that a CD stores information as 0s and 1s, while a record stores information as physical grooves on a vinyl disc. Additionally, a CD can store much more music than a record, and is less susceptible to damage from scratches or dust.
A CD is made through a process called replication. First, a glass master is created with all the digital information for the CD. This master is then used to create a stamper, which is used to press the information onto a polycarbonate disc. This disc is then coated with aluminum and a protective lacquer layer, and finally, the label and artwork are printed onto the disc.
The length of a CD's playing time is determined by the size of the pits and lands on the disc. The smaller the pits and lands, the more information can be stored on the disc, resulting in a longer playing time. Early CDs had a playing time of 74 minutes, but advancements in technology have allowed for longer playing times, with some CDs now able to hold up to 80 minutes of music.
To ensure the longevity of your CDs, it's important to handle them carefully and keep them in a safe, clean environment. Avoid touching the playing surface of the disc, as oils from your fingers can damage it. Store CDs in their cases when not in use to protect them from dust and scratches. It's also important to keep CDs away from heat and direct sunlight, as these can cause warping or damage to the disc.