What is "the Disk" in a Computer?
In a computer, the disk is usually not an actual circle-shaped disk, but instead refers to non-volatile memory, which is the kind of "permanent" computer memory where your files are saved. In other words, "disk" is the opposite of "RAM."
For example, when we say "save to disk," the "disk" is ANYWHERE you can save files to. So "the" disk is ALL your disks, all your hard disks, diskettes, SSDs, CDs, USB flash drives, etc. Anywhere you can save files to counts as part of "the" disk. Even though half of these aren't even disk-shaped nor do they contain any disks within.
The only exception I can imagine is the cloud. The cloud isn't part of the disk because it's not your computer, so instead of "save to disk" you'll see "save to cloud" in this case.
