I was helping a friend fix his computer recently, and something he said made me think.
Partitions. We all know what they are, right? He said his disk had three partitions, but I noticed it was four and pointed this out.
Interestingly, he thought the partition wasn't the area of the disk, but the dividing line between them. So, one disk divided into four areas by three partitions.
After all, a partition in a room is the wall itself, not the spaces on either side.