RTF
Rich Text Format: a document you can read as source.
Where it came from
RTF was created by Microsoft in 1987 to exchange documents across platforms and Word versions. Paradox: proprietary in spirit yet fully textual — an RTF file opens in Notepad and reads almost like TeX.
Its niche today is the clipboard (formatted copy-paste between apps often goes through RTF) and embedded editors that don't want a full DOCX parser.
How it works
RTF mixes text with backslash control words: «\b» starts bold, «\par» ends a paragraph, groups wrap in braces. Encodings are handled with escapes («\'e9», «\u1055?»).
The format is verbose (documents balloon versus DOCX) but trivially streamable: a parser is a finite-state machine — no zip, no XML.
UWC strips formatting and extracts clean text from RTF right in your browser.