File Extensions Explained: PDF, DOCX, XLSX, JPG, PNG
Understand file types so you open, upload and convert files correctly.
What a file extension is
The letters after the last dot in a file name – report.pdf, photo.jpg – are the extension. It tells Windows and your phone which app should open the file. Renaming the extension does not convert the file; photo.jpg renamed to photo.pdf is still a picture, just broken.
- Show extensions in Windows 11: File Explorer → View → Show → File name extensions.
- Windows 10: File Explorer → View tab → tick File name extensions.
Common extensions
| Extension | Type | Opens with | Notes |
|---|---|---|---|
| Document for sharing/printing | Edge, Chrome, Acrobat Reader | Same look on every device | |
| .docx / .doc | Word document | MS Word, Google Docs, LibreOffice | .doc is the old format |
| .xlsx / .csv | Spreadsheet / plain table | Excel, Google Sheets, LibreOffice Calc | CSV has no formatting or formulas |
| .pptx | Presentation | PowerPoint, Google Slides, Impress | |
| .jpg / .jpeg | Photo (compressed) | Photos app, any browser | Small size, slight quality loss |
| .png | Image (lossless) | Photos app | Best for screenshots, logos, text |
| .webp | Modern web image | Browsers, Photos app | Smaller than JPG/PNG |
| .mp4 / .mp3 | Video / audio | Media Player, VLC | |
| .zip / .rar / .7z | Compressed folder | File Explorer, 7-Zip | See ZIP guide |
| .txt | Plain text | Notepad | No formatting |
| .html | Web page | Browser | Can contain scripts – be careful with email attachments |
Extensions that can run programs (be careful)
| Extension | Why risky |
|---|---|
| .exe, .msi | Install or run software on Windows |
| .bat, .cmd, .ps1, .vbs, .js | Scripts that can change or delete files |
| .scr | Screensaver – actually a program |
| .apk | Android app – never install APKs sent on WhatsApp/SMS |
| .lnk | Shortcut that can launch hidden commands |
| .docm, .xlsm | Office files with macros – do not click “Enable content” for unknown files |
Converting properly
- Word → PDF: File → Save As → PDF.
- Image → PDF: open in Photos → Print → Microsoft Print to PDF.
- PNG → JPG (smaller): open in Paint → File → Save as → JPEG.
- PDF → Word: see PDF to Word.
- HEIC (iPhone photos) → JPG: on iPhone, Settings → Camera → Formats → Most Compatible; on Windows install “HEIF Image Extensions”.
Change which app opens a file type
Right-click a file → Open with → Choose another app → select the app → Always. Or Settings → Apps → Default apps → search “.pdf”.
File extension क्या है
File नाम में आख़िरी dot के बाद के अक्षर – report.pdf, photo.jpg – extension हैं। ये Windows और phone को बताते हैं कि file कौन सा app खोलेगा। Extension का नाम बदलने से file convert नहीं होती; photo.jpg का नाम photo.pdf करने पर भी वह picture ही है, बस टूटी हुई।
- Windows 11 में extensions दिखाएँ: File Explorer → View → Show → File name extensions।
- Windows 10: File Explorer → View tab → File name extensions tick करें।
आम extensions
| Extension | प्रकार | किससे खुलता है | ध्यान दें |
|---|---|---|---|
| Share/print के लिए document | Edge, Chrome, Acrobat Reader | हर device पर एक जैसा | |
| .docx / .doc | Word document | MS Word, Google Docs, LibreOffice | .doc पुराना format |
| .xlsx / .csv | Spreadsheet / सादी table | Excel, Google Sheets, LibreOffice Calc | CSV में formatting या formulas नहीं |
| .pptx | Presentation | PowerPoint, Google Slides, Impress | |
| .jpg / .jpeg | Photo (compressed) | Photos app, कोई भी browser | छोटा size, थोड़ी quality कम |
| .png | Image (lossless) | Photos app | Screenshots, logos, text के लिए सबसे अच्छा |
| .webp | आधुनिक web image | Browsers, Photos app | JPG/PNG से छोटा |
| .mp4 / .mp3 | Video / audio | Media Player, VLC | |
| .zip / .rar / .7z | Compressed folder | File Explorer, 7-Zip | ZIP guide देखें |
| .txt | सादा text | Notepad | Formatting नहीं |
| .html | Web page | Browser | Scripts हो सकते हैं – email attachments में सावधान |
Programs चला सकने वाले extensions (सावधान)
| Extension | क्यों ख़तरनाक |
|---|---|
| .exe, .msi | Windows पर software install या चलाते हैं |
| .bat, .cmd, .ps1, .vbs, .js | Files बदल या delete कर सकने वाली scripts |
| .scr | Screensaver – असल में program |
| .apk | Android app – WhatsApp/SMS पर भेजे APK कभी install न करें |
| .lnk | छिपे commands चला सकने वाला shortcut |
| .docm, .xlsm | Macros वाली Office files – अनजान files पर “Enable content” न दबाएँ |
ठीक से convert करना
- Word → PDF: File → Save As → PDF।
- Image → PDF: Photos में खोलें → Print → Microsoft Print to PDF।
- PNG → JPG (छोटा): Paint में खोलें → File → Save as → JPEG।
- PDF → Word: PDF से Word देखें।
- HEIC (iPhone photos) → JPG: iPhone पर Settings → Camera → Formats → Most Compatible; Windows पर “HEIF Image Extensions” install करें।
कौन सा app file type खोले, बदलें
File पर right-click → Open with → Choose another app → app चुनें → Always। या Settings → Apps → Default apps → “.pdf” search करें।
Frequently Asked Questions
How do I see file extensions in Windows 11?
Open File Explorer → View → Show → File name extensions.
Can I convert a file by renaming its extension?
No. Renaming only changes the label; the content stays in the old format and may not open. Use Save As/Export or a converter.
Which file extensions are dangerous in emails?
.exe, .msi, .scr, .bat, .js, .vbs, .apk, .lnk and macro files (.docm, .xlsm) from unknown senders. Also be careful with .zip and .html attachments you did not expect.
