When you’re troubleshooting your computer or installing a new operating system, you may need to “boot from a disc” or USB device (such as an external hard drive or flash drive). Here’s what that means — and how to do it.

Dear Lifehacker, I have never used the Safe Eject option when removing USB drives from my laptop. Instead, I just yank it out once the files have been transferred or saved. I'm pretty certain I'm not in the minority here. Is this bad?

Who doesn't hate carrying around their laptop? Even the lightest ones weigh a couple of pounds and can be a huge burden to lug around the city. That's where portable apps, ones stored on a USB drive, come in.

Dear Lifehacker, I always take my thumb drive wherever I go. I'm also a bit absentminded. I want to guarantee my thumb drive gets returned to me if I ever lose it. My idea is to have malware hidden on the drive in a specific folder labelled 'porn101' or 'myprivatefiles'. If the person opens that file, it will automatically encrypt their computer and ask them to email me to get the unlock code. (I will give it to them once they return the thumb drive to me, of course.)

Which brings me to my question - is this legal? It's not like I'm demanding money or anything. I just want my property back!

Flash drives can come in all sorts of fun shapes and sizes (my current favourite is shaped like R2-D2), but wouldn't it be cool to make one with your own design? With a microwave kiln and some glass you can.

With the convenience of cloud storage, USB flash drives might seem like old news, but the best are portable, fast, near-indestructible and offer tons of space -- enough that they're worth having. Here are five of the best, with links to Australian deals.

Plugging a USB drive into a port on the front of a desktop is convenient, but you're also one knee-bump away from breaking the thing. Avoid the problem by using a flexible USB adaptor or extension cord to prevent damage.

Windows: If you find yourself leaving your USB drive in your work computer and cursing yourself after you arrive home, USB Guard will make sure you always remember to take your flash drive with you.

We've shown you how to manually create a bootable Mac OS X Lion DVD or thumb drive, but now an app called Lion DiskMaker can automate the process for you. You just download it, insert the media you want to use to create your install, and let it take care of the rest.

Windows: Whether you're looking to try out Linux or create a Windows troubleshooting tool, LiLi will create a powerful Linux thumb drive, letting you pick your distribution, save data between reboots, or even launch your mobile OS right from Windows.

Windows only: If you're sick of locking your computer and entering your password every time you come back to it, Predator will ease the process by using a thumb drive as a "key" that instantly locks and unlocks your computer.

Malware often spreads itself by using the Windows autorun feature to install itself on USB drives. USB Immunizer prevents that from happening by placing a special, non-removable version of the autorun.inf file on any USB drives or SD cards you choose, meaning they're not vulnerable to this form of attack.

Chances are you've accumulated a few spare thumb drives over the years, choosing new ones thanks to better form factors and increased capacities. But what do you do with the old ones that are just lying around? Here are our top 10 clever, fun and practical uses for your spare thumb drives.

We always like hearing about how posts on Lifehacker have helped people out. Reader Xavier took up our suggestion of labelling a USB key with your mobile phone number, and found that it worked for getting the key back even after a three-month break.

There are tons of awesome live, bootable Linux systems, but what if you need to run OS X? Reader Will shows us how to put a portable version of OS X on a thumb drive and boot it on (most) Intel computers.

Windows: If you're tired of managing five or six different live CDs for testing and troubleshooting, free program XBoot will help you merge them all onto one DVD or thumb drive, complete with a handy menu to choose between them.

We've featured a few ways to hide your data in plain sight, but DIYer Thice took a different approach: he actually hid a USB thumb drive inside his mouse.

Have you ever wanted a nice personalised copy of Ubuntu to take around with you? Even if you aren't well versed in the terminal, Remastersys makes it very easy to create a customised live CD from the Ubuntu you already have installed.

Whether you're trying to increase your security at an internet cafe, tunnel your way to your home computer from your cubicle, or leave no trace on your friend's borrowed computer, a flash drive turned portable privacy toolkit is invaluable.