Common file formats: when to use which
PDF, DOCX, CSV, JPEG, PNG, SVG, ZIP… which format to pick for a document, an image or an archive, and why.
Documents and text
| Format | Use for |
|---|---|
| Sharing a fixed document, identical on every device, ready to print | |
| DOCX / ODT | A document still meant to be edited (Word / LibreOffice) |
| TXT | Plain text with no formatting, universally readable |
| CSV | Simple tabular data, importable into any spreadsheet or database |
| MD (Markdown) | Technical documentation, READMEs, simple formatted text you can version |
Images
| Format | Use for |
|---|---|
| JPEG | Photos (lossy compression, small files) |
| PNG | Screenshots, logos, images needing transparency (lossless) |
| SVG | Vector logos and icons: crisp at any size |
| WebP | A modern JPEG/PNG replacement, smaller files (browser support is now near-universal) |
| HEIC | The default format on recent iPhone photos — convert to JPEG for compatibility |
Archives and compression
| Format | Notes |
|---|---|
| ZIP | The most universally compatible (Windows, macOS, Linux) |
| 7Z | Better compression ratio than ZIP, needs dedicated software |
| TAR.GZ | The standard on Linux/macOS, often used to distribute source code |
When in doubt about sharing a document outside your organization, PDF is the safest choice: guaranteed identical layout, and no need for the original software to open it.
Audio and video
| Format | Use for |
|---|---|
| MP3 | Compressed audio, compatible everywhere, good enough for everyday listening |
| FLAC | Lossless audio, for archiving or critical listening (larger files) |
| MP4 | The most universally compatible video format, a good quality/size trade-off |
| WebM | An open web video format, often smaller than MP4 at the same quality |
Spreadsheets and structured data
| Format | Use for |
|---|---|
| XLSX | An Excel workbook with formulas, formatting and multiple sheets |
| CSV | Simple tabular data exchange between different software |
| JSON | Structured data for an application or an API |
| XML | Structured data with more verbose syntax, still common in some legacy systems |
A CSV loses all formatting, formulas or multiple sheets from an Excel workbook — it's a raw data-exchange format, not a full XLSX replacement.
Converting from one format to another
Most common conversions (image, document, audio) don't need paid software: online tools, a program's built-in export options, or command-line tools like ffmpeg (audio/video) or ImageMagick (images) for repeated or automated use.
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