Complex sentence: Software distributed on bootable discs is often available for download in ISO image format and, like any other ISO image, may be written on, or "burned" to, a CD, DVD, or even a USB flash drive with any capable software.
Split into simpler sentences: Software distributed on bootable discs is often available for download in ISO image format. And like any other ISO image, it may be written on--or "burned" to--a CD, DVD, or even a USB flash drive with any capable software.