Base32, a derivation of Base64, is a notation for expressing large numbers in a form that can be conveniently and accurately transmitted between humans and computer systems. It uses an alphabet of A–Z, followed by 2–7 (thus "2" actually has a numerical value of 26). 0 and 1 are skipped due to their similarity with the letters O and I.

Base32 has two main advantages over Base64:

1. The resulting character set is all one case (usually represented as uppercase), which can often be beneficial when using a case-insensitive filesystem.
2. The result can be included in a URL without encoding any characters.

An earlier form of base 32 notation was used by programmers working on the Electrologica X1 to represent machine addresses, for example: 12-16 for 400.

References

• RFC 3548

Base32

Positional numeral systems