An optical disk drive reads and writes data to CDs, DVDs, and Blu-ray discs using a laser

An optical disk drive is a piece of hardware that uses a laser beam to read data from shiny discs — CDs, DVDs, and Blu-ray discs — and in some cases write data to them. The laser bounces off tiny pits and flat areas on the disc surface, and the drive interprets those reflections as 1s and 0s. It's fundamentally different from a hard drive or solid-state drive, which store data magnetically or electronically on a fixed internal component. An optical drive is external to your computer (or built into older laptops), and the disc itself is removable.

Most new computers no longer come with an optical drive built in. Laptops especially abandoned them years ago to save space and weight. But external USB optical drives still exist and cost between $20 and $60, and some people still need them — to install software from disc, back up data to DVDs, or play physical media they already own.

Key Takeaways

  • Optical drives use a laser to read data from discs; they cannot store data permanently the way a hard drive does.
  • Most modern computers do not include an optical drive, but external USB versions are still available and inexpensive.
  • A disc can hold between 700 MB (CD) and 50 GB (dual-layer Blu-ray), which is far less than a modern hard drive or SSD.
  • If you need to install software, play DVDs, or access old discs, an external optical drive is a practical alternative to replacing your computer.

How much data fits on each type of disc

The amount of data a disc can hold depends on its type. A standard CD holds about 700 MB — roughly enough for 80 minutes of audio or a few hundred photos. A single-layer DVD holds 4.7 GB, and a dual-layer DVD holds 8.5 GB. A single-layer Blu-ray disc holds 25 GB, and a dual-layer Blu-ray holds 50 GB.

For context, a modern hard drive or SSD typically starts at 256 GB and goes much higher. So optical discs are useful for small, specific tasks — backing up a folder of documents, sharing files with someone who has a disc drive, or keeping a physical copy of something important — but not for storing your entire digital life. They are also slower to read and write than modern storage, and they degrade over time if exposed to heat or light.

Why computers stopped including optical drives

Optical drives took up physical space, added weight to laptops, and required moving parts that could break. As internet speeds improved and cloud storage became standard, the need to physically transport data on discs dropped sharply. Software companies moved to digital downloads. Streaming services replaced DVD collections. Most people stopped burning CDs and DVDs.

Manufacturers removed optical drives to make laptops thinner and lighter, and to reduce manufacturing costs. Desktop computers held onto them longer, but even there they are now uncommon. The shift happened gradually between 2010 and 2015, and by now most people under 30 have never owned a computer with a built-in optical drive.

When you might still need an optical drive

You need an optical drive if you have physical media you want to use: old software installation discs, DVDs you own, CDs of music or data, or Blu-ray movies. You also need one if someone sends you a disc and you have no other way to read it. Some older software, especially specialized or professional programs, was only distributed on disc and may not be available as a digital read.

If you fall into one of these categories, buying an external USB optical drive is far cheaper than replacing your computer. A basic external DVD drive costs $25 to $40. A drive that reads and writes DVDs costs $30 to $50. A Blu-ray drive costs $50 to $100. Plug it in via USB, and your computer will recognize it when ready on Windows or Mac.

The difference between read-only and read-write drives

Some optical drives are read-only, meaning they can only read data from a disc — they cannot write to it or create new discs. Others are read-write drives, which can both read existing discs and write new data to blank discs (CD-R, DVD-R, Blu-ray-R, and rewritable versions of each).

If you only need to access discs you already have, a read-only drive is cheaper and simpler. If you want to back up files to disc, create music CDs, or burn video DVDs, you need a read-write drive. Most external drives sold today are read-write, so you have the option either way. The software to burn discs — Nero, ImgBurn, or built-in tools on Windows and Mac — is usually free or inexpensive.

Optical drives versus other storage options

If your goal is to back up data or move files between computers, an optical drive is rarely the best choice anymore. A USB flash drive holds far more data (32 GB to 1 TB), costs about the same, and is faster and more durable. Cloud storage like Google Drive or OneDrive is free up to a point and accessible from anywhere. An external hard drive or SSD gives you terabytes of storage for $50 to $150.

An optical drive makes sense only if you have a specific reason: you own physical media you need to access, you want to create discs for archival purposes (though even that is debatable, since discs degrade), or you need to install software that only comes on disc. For everything else, modern alternatives are faster, hold more data, and are easier to use.

Frequently Asked Questions

Can I use an external optical drive on a Mac?

Yes. Most external USB optical drives work on both Windows and Mac without additional software. Plug it in, and your Mac will recognize it. To burn discs on a Mac, use the built-in Disk Utility or third-party software like Toast Titanium.

How long do optical discs actually last?

Manufacturers claim 10 to 50 years depending on the disc type and quality, but real-world lifespan varies widely. Discs stored in cool, dark places last longer. Exposure to heat, humidity, and light degrades them faster. For long-term archival, optical media is not considered reliable — hard drives or cloud storage are safer bets.

Do I need a special drive to read Blu-ray discs?

Yes. A standard DVD drive cannot read Blu-ray discs. You need a Blu-ray drive, which is more expensive ($50 to $100 for external models) but can also read DVDs and CDs. If you only need to read DVDs, a standard DVD drive is sufficient and cheaper.

What if my computer doesn't recognize the external optical drive?

First, try a different USB port. If that doesn't work, restart your computer with the drive plugged in. On Windows, check Device Manager to see if the drive appears with a warning icon — if so, update the driver. On Mac, the drive should appear in Disk Utility. If it still doesn't work, the drive may be faulty or incompatible with your system.