Like the more common Base64 encoding, Base32 encoding is a method for turning binary data into a string composed of a small, defined set of ASCII characters. Base64 takes advantage of the entire alphabet in both upper and lower case, the digits 0 to 9 and the '+' and '/' symbols. This can be problematic where, for example, the encoded data needs to be used as part of a URL where the '+' and '/' symbols have special meaning and where case-sensitivity can cause problems.
Base32 addresses these issues by using a further reduced set of characters - the entire alphabet (but only one case) and the digits 2 to 7. The digits '0' and '1' are ommitted due to their similarity to the letters 'O' and 'I'. This makes Base32 even more useful in situations where human readability is a concern.