If you've ever hit "Save As" in a word processor and paused at the format dropdown, you've run into this: DOCX, ODT, and RTF all do roughly the same job - store text plus formatting - but for different reasons, aimed at different situations.
DOCX: the default for most people
DOCX is Microsoft Word's modern format (the successor to the older .doc), and it's the closest thing to a universal standard for word processing documents. Word, Google Docs, LibreOffice, Apple Pages, and most other software all read and write it natively. Unless you have a specific reason to use something else, this is almost always the right default - it's what most people expect when you send them a document.
ODT: the open-standard alternative
ODT (OpenDocument Text) is the native format of LibreOffice and OpenOffice, and it's built on an open, publicly documented standard (as opposed to DOCX, which - while widely supported - is still fundamentally a Microsoft format). Some organizations, especially government agencies and institutions with open-format requirements, specifically require or prefer ODT for exactly that reason.
Functionally, it does the same job as DOCX - text, formatting, images, tables. The difference is more about which ecosystem and openness philosophy you're working in than any real capability gap for everyday use.
RTF: maximum compatibility, minimum features
RTF (Rich Text Format) is older and much simpler than either of the above. Its entire reason to exist is compatibility - an RTF file can be opened by an enormous range of software, including very old programs, because the format itself has stayed deliberately simple for decades. The trade-off is that it doesn't support the more advanced features modern formats have (think complex layouts, embedded objects, some styling options) and tends to produce noticeably larger files for the same content, since it's a much less efficient way to encode formatting.
Use it when you genuinely need broad compatibility with older or unusual software, and don't need advanced formatting - it's a "lowest common denominator" choice more than an everyday one.
Quick reference
| Format | Best for | |---|---| | DOCX | The default choice for almost everyone, almost every time | | ODT | Open-standard requirements, or if you're working primarily in LibreOffice/OpenOffice | | RTF | Maximum compatibility with old or unusual software, simple formatting only |
Converting between them
- DOCX to ODT
- DOCX to RTF
- Browse all document tools for every other combination, including plain text and HTML
In practice, most people never need to think about this at all - but if someone specifically asks you for one of these formats over another, now you know why.