An inquisitive youngster asks: What are the Windows A- and B- drives used for?
In Windows you have a C: drive and everything beyond that is labeled with the following letter.
So your second drive is D:, your DVD is E: and if you put in a USB stick it becomes F: and the following drive G: and so on and so on, etc.
But then, what and where are A: and B:?
Unfortunately, the people who are old enough to know the answer are all dead by now.