Archive file extensions guide
The letters at the end of a filename tell you whether to extract, mount, inspect, or ask for a different file.
| Extension | What it usually means | Best first step |
|---|---|---|
| .zip | Common compressed archive | Use built-in tools first |
| .rar | RAR archive, sometimes multi-part | Use a trusted extractor |
| .7z | 7-Zip archive with strong compression | Use 7-Zip, Keka, or similar |
| .tar.gz | Compressed tar archive, common in software | Extract into a clean folder |
| .iso | Disk image | Mount before extracting |
| .dmg | Mac disk image | Open on Mac; avoid Windows workarounds unless necessary |
Why extensions matter
A file extension is not a guarantee of safety, but it gives you the first clue about workflow. Treating an ISO like a ZIP can confuse you. Treating a suspicious executable inside a ZIP like a harmless document can create risk. The safest habit is to identify the format, choose the simplest trustworthy method, and inspect the extracted contents before running anything.
Double extensions
Be careful with names like invoice.pdf.zip or photos.jpg.exe. Some are legitimate. Others are designed to make a risky file look familiar. Turn on full filename visibility on your device when handling files from unknown sources.