One hot trend on the rise back in 2006 was the use of Live Linux USB Boot. Allowing for a PC user to boot and run an ISO file of a Linux operating system Live from a USB flash drive.
In the most basic form, a Live environment lets the PC user test drive the operating system to see if they like it before doing a full install to a computer's physically attached internal hard drive. Applications within can also be used in emergencies when you need to fix or repair a computer that has a virus or file corruption. Some might use it when a computer has encountered complete hard drive failure and they need to get to the internet, check their e-mail etc. One of the best things about running Linux Live is that it leaves no traces behind on the client computer because it runs completely from it's own media and or system memory.
Advantages and Disadvantages of using Live Linux
Advantages: For the most part, the advantages are great. It's portable, able to run on most PC's today, and is virtually hack-proof and virus free. However, there is one major drawback to running Linux via a CD drive keeping it from becoming a fully capable operating environment that you might use every day.
Disadvantages: Live Linux natively contains virtually no read/write support. That is to say that once a Live CD is created, you can't easily edit it or save even your basic setting changes, favorite bookmarks, e-mail etc back to the same CD. Well, there are some works in progress that allow the use of a CDRW drive for read/write support. Though writing changes to a CD is typically too slow for the average user to feel comfortable using this method.
Running Live Linux from a USB Flash Drive
This is where USB flash drive technology comes in. Most newer motherboards have adopted the faster USB standard (2.0). Many of these boards also support booting directly from a USB Device. With these recent advancements, the merging of live Linux and USB Pen drives becomes natural. We can benefit from the increased speed, have read/write capability and even more portability using a flash drive vs a live CD to Live Linux USB Boot.
If you'd like to experiment with running Linux on a flash drive, you can find a complete list of walkthrough tutorials at Pen Drive Linux Site.
Pen Drive Linux explains how install various Live Linux versions to a pen drive. This allows a person to bring a portable Linux along with their personal settings with them to quickly boot on any computer that supports UEFI or BIOS USB booting.