I recently saw it mentioned that another site's URL ids were consecutive numbers in base 52, and then base 36 here. I was previously only aware of the use of ba

I recently saw it mentioned that another site's URL ids were consecutive numbers in base 52, and then base 36 here. I was previously only aware of the use of base 64, so my interest was piqued — why choose one over the other? It looks like the reason is that in base 36 information can be encoded in the 26 characters of the alphabet plus 10 numeric characters. In base 52 you can use the same, but case-sensitive and possibly without vowels. This makes it work nicely in URLs. I was going to ask the significance but thought I'd post what I found instead.