application/rtf

Microsoft's pre-XML interchange format for word processing: plain ASCII control words in braces, first shipped with Word 3.0 for the Mac in 1987 and frozen at spec version 1.9.1 in 2008, after which Microsoft stopped developing it. It survives because it is the format that opens everywhere — every word processor of the last three decades reads it — and because its plain-text syntax made it a favorite container for malware, which is why mail gateways scan .rtf attachments with particular suspicion. The registry also lists text/rtf; both circulate, application/rtf is the safer bet. Every file begins with the literal group {\rtf1.

Defined by IANA registration — application/rtf · IANA registration. Registry facts from the IANA media-types registry via mime-db.