Why Hard disk labeling starts with C rather than A?

Question

After installing OS, When opening "MY Computer" it shows first hard disk as "C", why so?

Why Hard disk labeling starts with C rather than A?

Answer 1

Because History.

As you can see any self-respecting IBM PC from the early 1980s had two 5-1/4" floppy drives (black):

The first floppy drive, the one on the left, is A: and second, the one on the right is B:. When one of those new-fangled hard-disks was added, it became C:. All software assumed that this was how the drives were labeled.

Eventually, when the hard drive became standard, any application program that needed to access an operating system file, it knew to look for it on drive C:. Over time, floppy drives slowly disappeared. But, the assumption that key OS files were on drive C: remained. That is why the first hard disk is C:.

Answer 2

C:\ is the default drive because Windows is built on DOS. In early DOS computers there wasn't a hard disk; only floppy drives. These were A:\ for the first one and B:\ for the second if the computer had two. By the time hard disks came around, A:\ and B:\ were taken so C:\ was used for the default hard disk. We still use C:\ because to maintain compatibility with older software.