What is an optical drive? A guide to how your computer reads CDs, DVDs, and Blu-ray discs

• Optical drives let your computer read and interact with discs like CDs, DVDs, and Blu-rays.
• While nearly every computer had them a few years ago, they're rare to see on new computers now.
• If you need an optical drive but your computer doesn't have one, you can buy an external optical drive.

Optical drives were once so common that virtually every computer came with one, or even two. Now this storage solution is quickly becoming obsolete - it's increasingly rare to find a mainstream desktop or laptop computer with a built-in optical drive.

You can still find them, however, on several other devices. These include game consoles, DVD and Blu-ray players, and car stereos.

Here's everything to know about optical drives, including what they do, how they work, and what to do if you need one.

What are optical drives?

In the simplest terms, an optical drive is the piece of hardware that lets a device read and interact with a disc. These discs can be CDs, DVDs, Blu-rays, game discs, and more.

All optical drives are based on the same fundamental technology. An optical drive is composed of a laser that's used to read and write data that's encoded in a plastic disc which spins on a platter. Depending on the specific kind of optical drive - CD, DVD or Blu-ray - the wavelength of the laser will vary, along with the rotational speed of the disc.

The CD was the first kind of optical disc, initially designed without regard for computer storage. The first prototype arrived in 1979 to play back music but was adapted into the CD-ROM format in 1985, capable of storing 700MB of data, which at the time was substantially more storage space than commonly available in hard disk drives (HDDs).

Optical formats evolved over the years; DVDs debuted in 1997 to play movies in standard definition format (720x480 pixels), and early DVD-ROM discs could store 4.7GB. So-called dual-layer DVDs could store 8.5GB, and the format went up from there with many additional variations. A dual-layer BD-ROM can store 50GB.

Regardless of the internal details, most optical drives connect to a computer motherboard with a data cable and power cable, and feature an open/close button that controls access to the disc tray. Some optical drives dispense with the tray entirely; you simply feed the disc into a narrow slot, like in a car's CD player.

Types of optical media in use today

The optical drive exists to accommodate media, and there's a bewildering array of optical media formats.

That's a consequence of the decades-long development process that optical drives went through. Many different companies developed different versions of optical drives and optical media, often competitively, rarely ever collaborating.

The good news is that, in general, most modern optical drives can read and write most common formats.

• Read-only formats: Some optical discs are read-only, which means they can't be used to store new data, and the "-ROM" suffix is used to indicate this format. Commercial software, when it ships on disc, is commonly sold on CD-ROM and DVD-ROM, while read-only Blu-ray is rarely used for anything except movie distribution (and even that is quickly being supplanted by streaming services).
• Recordable and rewritable discs: Many optical media formats have a suffix that includes an "R," which indicates that the disc can be written to a single time, so once the disc is filled with new data, it is permanent. A "RW" disc is rewritable, which indicates that you can write, erase, and rewrite data to it multiple times, like a regular hard or flash drive (though many RW discs have limitations on how many times they can be rewritten). Some common formats include: CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW and others.
• Rewritable Blu-ray formats: These exist but, since they arrived so recently (starting around 2003, with new versions arriving as recently as 2017), it isn't a popular consumer format. They've already been made obsolete by a host of competing technologies like flash drives, high-capacity HDDs, SSDs, and cloud storage.

How to read or write optical disks without an optical drive

While most older computers have a built-in optical drive, few new computers include one - a sign that most people don't need these drives anymore. Most new software and data is downloaded from the internet rather than installed from a disc, and most common place to find optical drives now is on game consoles.

Even so, you might occasionally have the need to read or write a disc on your computer. Here are some ways to work around not having an optical drive in your computer:

• Look online. If you need to install software from a CD-ROM or DVD-ROM, check the internet. In many cases, the program, utility, or device drivers you need will now be found on the manufacturer's website or archived on another site.
• Use another computer or a USB flash drive. If you need to recover files (like backups or photos) from an optical disc, you can probably open the disc on another computer that has an optical drive and then copy the files you need to a USB flash drive. Even a small flash drive should have more capacity than even the largest optical discs.
• Purchase an external optical drive. You can connect an external optical drive to your computer via USB. External drives are so inexpensive - you can routinely find CD/DVD drives online for $25 or less - that it might make sense to purchase one and keep it in the closet for those rare occasions when you need it.

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