Base64 binary to text encoding. Encodes binary data as a sequence of printable ASCII characters. Commonly used for the transfer of binary content by email. The Base64 encoding is described in internet standard recommendations RFC 1421 and 2045. ASCII format. Uses the 52 uppercase and lowercase letters of the Roman alphabet, the numerals 0 to 9, and the characters and to form a positional numeral system using a base of 64. The character is used for padding Base64-encoded data.