> Once upon a time, it was determined that 63 (512-byte) sectors was far more than anybody would be able to fit into a single disk track.
> [...] it made sense to align partitions so that the data began at the beginning of a track. So, traditionally, the first partition on a drive begins at (logical) sector 63, the last sector of the first track.
> That sector holds the boot block; any filesystem stored on the partition will follow at the beginning of the next track.
I think the two last paragraphs are incorrect. Logical sector 63 is the first sector of the second track, sectors 0-62 are in the first track. So the first partition is completely (both administrative overhead and data) located on the second track.
Not that this matters now that legacy emulated geometry is finally getting obsoleted.