Base64 is a means of encoding binary data into
printable text characters in a way that is independent of
the character set of the underlying computer. This independence of
the underlying character set is unique to base64, and
is not provided by other systems such as the traditional
Unix uuencode.
Base64 is specified as part of the MIME
protocol.
The output of a base64 encoder consists of 64
characters (A-Z, a-z, 0-9, + and /).