Editing MIME (section)

===Content-Type===
This header field indicates the [[media type]] of the message content, consisting of a ''type'' and ''subtype'', for example
 Content-Type: text/plain

Through the use of the ''multipart'' type, MIME allows mail messages to have parts arranged in a [[tree structure]] where the leaf nodes are any non-multipart content type and the non-leaf nodes are any of a variety of multipart types.
This mechanism supports (non-exhaustively):
* '''simple text messages using ''text/plain''''' (the default value for "Content-Type: ")
* text plus attachments (''multipart/mixed'' with a ''text/plain'' part and other non-text parts). A MIME message including an attached file generally indicates the file's original name with the "Content-Disposition" header, so that the type of file is indicated both by the MIME content-type and the (usually [[Operating System|OS]]-specific) [[filename extension]]
* reply with original attached (''multipart/mixed'' with a ''text/plain'' part and the original message as a ''message/rfc822'' part)
* alternative content, such as a message sent in both plain text and another format such as [[HTML]] (''multipart/alternative'' with the same content in ''text/plain'' and ''text/html'' forms)
* image, audio, video and application (for example, ''image/jpeg'', ''audio/mp3'', ''video/mp4'', ''application/msword'', among others).