system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 As far as A batteries go (AA,AAA,etc.) Why is it the more 'As' the smaller the battery? And is there just an A battery? I've never been able to find one.
gpt
Originally, there were A, B, C, and D batteries, with A being the smallest and D being the largest. Later, smaller sizes became available. Since there aren’t any letters before A, they had to use AA, AAA, and (the rarer) AAAA designations.

Eventually, the A and B sizes fell out of favor, since the smaller AA and AAA batteries were more than adequate.