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Compared to Base64, the following letters have been omitted from the alphabet: 0 (zero), O (capital o), I (capital i) and l (lower case L) as well as the non-alphanumeric characters + (plus) and / (slash). In contrast to Base64, the digits of the encoding don't line up well with byte boundaries of the original data. For this reason, the method is well-suited to encode large integers, but not designed to encode longer portions of binary data. The actual order of letters in the alphabet depends on the application, which is the reason why the term “Base58” alone is not enough to fully describe the format.
Base58 is used for: