Bitcoin addresses are encoded using the Base58Check encoding. This encoding is used to limit the confusion between various characters, such as 0OIl as they can look the same in different fonts. The encoding basically takes the binary byte arrays and converts them into human-readable strings. This string is composed by utilizing a set of 58 alphanumeric symbols. More explanation and logic can be found in the base58.h source file (https://github.com/bitcoin/bitcoin/blob/master/src/base58.h) in the bitcoin source code:
/*** Why base-58 instead of standard base-64 encoding?* - Don't want 0OIl characters that look the same in some fonts and* could be used to create visually identical looking data.* - A string with non-alphanumeric ...
