One piece missing from the description is the "write protect" notch in the 8" & 5 1/4" floppies. if the notch was present, the biscuit was read/write on that side. If it was not present, or was covered with a piece of tape, that side became read-only. If looking the diskette from the top, the notch would be in the upper right edge.
Early drives only wrote on one side of the diskettes. Someone discovered that diskettes had magnetic material on both side, so the diskette could be flipped and written on, doubling the storage. A notch would have to be cut to make it read/write, but it worked relatively reliably.
Later drives got second read/write heads and the flipping went away.
On the 3 1/2" diskettes this became a sliding tab. But, in their wisdom they flipped the concept. They reversed it. "missing" or open notch meant write-protect, and closed notch meant read/write.
The magnetic material on both sides had a very practical reason to be workable in all kind of floppy drives.
For example the write/read-head in a C64 floppy was placed on the bottom, so the down side of the floppy got magnetized. But the head of the floppy drive from a Atari 800 was placed at the top, so the upper side got magnetized.
So basically, when a floppy was sold as 1S (single sided) this was pure marketing. :) At least for the most floppy drives.
There's also a second thing, the "index hole". On real 2S floppy there are 2, one for each side. But most of the drives didn't care about this index hole. So, this wasn't relevant for C64 users and such.
Early drives only wrote on one side of the diskettes. Someone discovered that diskettes had magnetic material on both side, so the diskette could be flipped and written on, doubling the storage. A notch would have to be cut to make it read/write, but it worked relatively reliably.
Later drives got second read/write heads and the flipping went away.
On the 3 1/2" diskettes this became a sliding tab. But, in their wisdom they flipped the concept. They reversed it. "missing" or open notch meant write-protect, and closed notch meant read/write.