OK, you can laugh, this is poorly said, but it's a problem a lot of people among us really have.
Each of the tools I use is on a bootable CD/DVD, saved as an iso file.
Each time I want to use such a tool, I must first burn this iso file to a rewritable CD, then boot on that CD and do my job.
The next job needs another bootable CD, so another iso file, so erase my rewritable media and burn the other iso.
Things could be far simpler if I could boot on a removable media, which would lead me to a menu where I could choose between several iso files, and then boot from that iso file as if it were a bootable CD on my CD reader.
There are several methods for creating a bootable USB drive from an iso file, but this is not the iso file directly used, this is a bootloader loading files extracted from an iso. Which means one iso, one USB drive.
i'll support and recommend the USB bootable option... much quicker although creating the USB bootable would probably be not as easy as burning an ISO to a DVD/CD