When people today want to listen to their favorite music or watch their favorite movie, they generally simply turn on their device of choice, find what they are looking for, and hit play. Whether that means going to YouTube or using a streaming app on your TV, the technology is quite similar.

A server at a data center somewhere is housing the music or video you want to enjoy, and when you request it, the service sends it through the Internet to your device, which holds it temporarily in memory while you are watching. Or, more likely, it holds a small portion of it in memory, downloading only the portion you need at any given moment.

While there is no denying the fact that streaming is an incredible and very convenient technology, it certainly isn’t the first way that people enjoyed media.

For those who lived in the 90s and 2000s, the technology of choice was optical media, which included CDs, DVDs, and Blu-Ray. All of these are just variations and advancements on the same type of technology, and the way they work is quite impressive.

This technology uses a tiny laser to read digital information off of a disc. That information was etched onto the disk (using another laser) in tiny patterns.

There are just two options for these patterns. Either microscopic depressions known as pits or flat areas known as lands. On a CD, the pits and lands are just a few micrometers in length. For those who don’t know, a micrometer is .001 millimeters. For a DVD and BluRay, they are .5 microns (500 nanometers) and 125 nanometers deep.

Once encoded, the pits and lands serve as binary data (1s and 0s) that any computer device can understand.

When the computer reads that information from the media, it can translate it into electrical signals, which then become music or video. Of course, you can also store other types of information on any of these disks.

The fact that the data is physically etched into the disk means that as long as the surface of the disk is protected, it can last a very long time, making it good for longer term storage (in the right protective case).

While most CDs and DVDs were commercially produced, there was also the option to use a CD-RW drive on your computer, which stood for Compact Disc-ReWritable. Along with those users would have a CDR or CDRW, which was a disc that had a thin layer of photosensitive organic dye sitting on the surface of a reflective layer.

The drive would have a laser that can read the medium as well as one that was more powerful and could actually melt it to etch data onto its surface. This is why it was called ‘burning’ a CD. Some of them could only be burned once, and others were made so that they could be burned over multiple times.

While most people today don’t use these devices, the technology is still very impressive. In some scenarios where offline storage of data is important, optical media like this is still one of the best and most efficient options available.

So, if you ever have the opportunity to use a CD or DVD, make sure you appreciate just how impressive the technology really is.

If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.