mime format. what is it?

You can read more in here http://en.wikipedia.org/wiki/MIME Multipurpose Internet Mail Extensions (MIME) is an Internet Standard that extends the format of e-mail to support text in character sets other than US-ASCII, non-text attachments, multi-part message bodies, and header information in non-ASCII character sets. Virtually all human-written Internet e-mail and a fairly large proportion of automated e-mail is transmitted via SMTP in MIME format. Internet e-mail is so closely associated with the SMTP and MIME standards that it is sometimes called SMTP/MIME e-mail. The content types defined by MIME standards are also of growing importance outside of e-mail, such as in communication protocols like HTTP for the World Wide Web. MIME is also a fundamental component of communication protocols such as HTTP, which requires that data be transmitted in the context of e-mail-like messages, even though the data may not actually be e-mail.