Confidence votes 33. First of all you are probably a 'rent asking this and not every word in the dictionary a teen has a slang word for, so remember that and don't critcize them just because they are WAY cooler than the kids next door!
When Raw Disk Image type is not mentioned explicitly in this guide, we are referring to the Backup Disk Image. Another file format supported is ISO image. ISO images are used to store a copy of CD/DVD/Blue-ray disc in a file and stand apart from actual disk images.
A virtual disk of either type can be stored on either type of physical hard disk. That is, the files that make up an IDE virtual disk can be stored on either an IDE hard disk or a SCSI hard disk. So can the files that make up a SCSI virtual disk. They can also be stored on other types of fast-access storage media, such as DVD-ROM or CD-ROM discs.