Computers normally run an operating system installed on their hard drives, whether it’s Windows, OS X, or Linux. But they can also boot from removable media devices, allowing you to boot a Linux desktop from a USB drive or CD.

Such Linux environments were originally named “live CDs” because they were burnt to a CD, but these days you’ll have better luck if you install them on a USB drive instead. USB drives are significantly faster than CDs and DVDs.

How a Live CD or USB Drive Works

When you boot your computer, it normally boots the operating system located on its hard drive. However, computers can also boot operating systems located on other devices. For example, when you install Windows, your computer boots from a CD, DVD, or USB stick, loads the Windows installer, and installs Windows onto your hard drive.

Live Linux systems — either live CDs or USB drives — take advantage of this feature to run entirely from a CD or USB stick. When you insert the USB drive or CD into your computer and restart, your computer will boot from that device. The live environment works entirely in your computer’s RAM, writing nothing to disk. When you’re done, you can reboot your computer and remove the USB drive or disc. The computer will be left exactly as it was.

In essence, a live Linux system works just like a typical operating system installer. But, instead of installing an operating system, it gives you a desktop that you can use without installation.

Why Not Windows Live Media?

Some of you will wonder why we’re not recommending a Windows-based live environment instead of Linux. Well, it’s simple — Microsoft doesn’t offer this feature to average people. Windows 8 includes a “Windows To Go” feature that allows users to take a Windows 8 system with them on a USB drive and boot it on any PC, but this feature is only available in Windows 8 Enterprise, the edition meant for businesses. If you’re an average person, you’ll have to stick with Linux.

Uses for a Live CD or USB Drive

Live environments have a number of uses, even for people who have never used Linux before:

  • Use a Secure Desktop For Online Banking and More: Some banks actually recommend you boot from a Linux live CD or USB drive before doing online banking. This is particularly useful if you want to do online banking on someone else’s computer and you’re not sure if it’s secure. Because of the way the live environment works, even if the Windows system installed on the computer is full of malware, no malware can run in your live environment. It will be a clean, secure system.
  • Try Out Linux: If you’re interested in giving Linux a test drive, you can do so by booting a live USB drive or CD on your computer — no changes to your computer required.
  • Troubleshoot Windows PCs: Linux offers a wide variety of Windows troubleshooting tools, so you could use your live Linux environment to partition a Windows system, recover deleted files, reset lost user account passwords, and more.
  • Take a Secure Operating System With You Everywhere: If you’re using a Live USB stick, you can choose to reserve part of the storage space for your personal files. You could then boot the USB stick on any system and your personal files and settings would be there.

RELATED: Securely Access Online Banking and Email on Untrusted Computers

Linux Live Environment Options

These days, nearly every Linux distribution offers a live desktop for you to try. The main installer media they provide often functions as a live environment. For example, you don’t have anything special to use a live Ubuntu environment — just download the main Ubuntu image, burn it to a disc or use UNetbootin to copy it to a USB drive, and boot from it. Choose to try Ubuntu instead of install it and you’ll get a desktop you can use without any installation required.

Knoppix was the original Linux live CD, and it’s still actively developed and available for download today. You may also be interested in Puppy Linux, an extremely minimal and slimmed down live system that can be installed to tiny USB sticks and easily run on older computer. Puppy only takes about 100 MB when installed on a USB stick.

Store Data, or Fresh Every Time?

If you choose to put the data on a USB drive, you’ll be able to choose whether you want to reserve part of the drive for your personal files. If you do, you can save files and change settings in the live environment and your changes will be saved to your USB drive. If you don’t, you’ll have a fresh system each time you start your USB drive. If you use a CD or DVD, there’s no way to reserve part of the live environment for your personal files. It will be entirely read-only.

Some live environments also offer encryption, so you can choose to encrypt your personal files. If you don’t use a system with encryption, bear in mind that anyone who gets your USB drive could look at any files you saved on it — just like they could look at the files on your laptop’s hard drive after stealing it.

In a way, Linux live environments are like portable applications — but they’re an entire portable operating system you can take with you between computers.

Image Credit: Wouter Vandenneucker on Flickr

Profile Photo for Chris Hoffman Chris Hoffman
Chris Hoffman is Editor-in-Chief of How-To Geek. He's written about technology for over a decade and was a PCWorld columnist for two years. Chris has written for The New York Times and Reader's Digest, been interviewed as a technology expert on TV stations like Miami's NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read more than one billion times---and that's just here at How-To Geek.
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