DOCX file format
DOCX is the Word document format since Office 2007 — an open XML standard that opens in Word, Google Docs, LibreOffice and practically every modern editor.
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What is DOCX?
DOCX arrived with Office 2007 as part of Office Open XML, later ratified as ECMA-376 and ISO/IEC 29500. The switch mattered because the old .doc format was an undocumented binary blob; DOCX is a documented, inspectable standard, which is why non-Microsoft software can read and write it reliably rather than guessing.
A DOCX file is actually a ZIP archive. Rename one to .zip, open it, and you will find the text in `word/document.xml`, images in a media folder and styles in their own files. That structure is why DOCX is far smaller than DOC — XML compresses extremely well — and why a partially damaged file can often be repaired by extracting what still reads.
The one thing DOCX does not carry is your fonts. It references them by name and expects the opening machine to have them, so a document typeset in a font the recipient lacks reflows with different line breaks and page counts. When the layout must not move, PDF is the format to send, not DOCX.
| Extension | .docx |
|---|---|
| Category | Document |
| MIME type | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Released | 2007 |
| Developed by | Microsoft |
| Compression | Lossless |
DOCX: frequently asked questions
- Why is DOCX so much smaller than DOC?
- Because it is a ZIP archive containing XML. Text compresses to a fraction of its size, while the old binary DOC format stored everything uncompressed along with editing history and slack space. The same document commonly shrinks by 50-75% when saved as DOCX.
- Is a DOCX file really a ZIP file?
- Yes. Copy it, rename the copy to .zip and any archive tool will open it, revealing the XML that describes your text, the images you inserted and the style definitions. This is genuinely useful for pulling an image out of a document without opening Word.
- Why does my DOCX look different on another computer?
- Almost always fonts. DOCX stores font names, not the fonts themselves, so a machine without your typeface substitutes another and the text reflows — different line breaks, different page count. Export to PDF when the layout has to stay exactly as you set it.
- Can I open a DOCX without Microsoft Word?
- Yes. Google Docs, LibreOffice Writer, Apple Pages, WPS Office and every mainstream mobile office app read and write DOCX. Complex features like tracked changes, macros and elaborate layouts can shift slightly, but ordinary documents open faithfully.
- DOCX or PDF — which should I send?
- Send DOCX when the recipient needs to edit, and PDF when they only need to read. PDF locks the layout and fonts so the document looks identical everywhere; DOCX stays editable but depends on the reader having compatible software and fonts.
- My DOCX is corrupted — can it be recovered?
- Often, yes. Because the file is a ZIP archive, an archive tool can sometimes extract the intact parts, and `word/document.xml` alone holds the text. Word's own "Open and Repair" option is worth trying first; converting the file is another way to force a clean rewrite.