An encoding method that converts binary data into ASCII text and vice versa. It is commonly used to send non-text files via the Internet's e-mail system (see MIME). Base64 divides each set of three bytes of the original data into four 6-bit units, which it represents as four 7-bit ASCII characters. This typically increases the original file by about a third. See quoted printable encoding.
Other features include support for GIF and JPEG, Base64, UUdecode and server authentication, an easy-to-use interface, an ability to download only selected pictures of a group and built-in tools such as zoom in, zoom out and flip.