ZIP, RAR and 7Z Explained: How File Archives Work
What compression archives are, how ZIP, RAR, 7Z and TAR.GZ differ, and how to open, convert and share archives safely.
Archives bundle many files into one and usually make them smaller. They are everywhere: software downloads, email attachments, photo collections, website backups. Yet a RAR or 7Z file sent to the wrong person often ends in “I can’t open this”. Understanding the main formats helps you choose the right one and open anything you receive.
What an archive does
An archive does two jobs:
- Bundlingpacking many files and folders into a single file, preserving names, folder structure and dates.
- Compressionreducing size by finding and encoding repeated patterns in the data.
How much an archive shrinks depends on the content. Text, documents and spreadsheets compress very well, often by 70 to 90%. Photos, videos, MP3s and PDFs are usually already compressed, so archiving them saves little space. The main benefit is bundling.
The main formats
ZIP
ZIP is the universal archive format. Windows, macOS, Linux, iOS and Android can all open ZIP files without extra software. Compression is good rather than exceptional. ZIP supports password protection (modern AES encryption is strong; old “ZipCrypto” is weak). Use ZIP for sharing with anyone.
RAR
RAR was made for WinRAR and is owned by its makers. It compresses well, supports recovery records that can repair damaged archives, and can split large archives into parts. However, most operating systems cannot open RAR files natively, and creating RAR files requires licensed software. If you receive a RAR, you can open or convert it with RAR to ZIP.
7Z
7Z is the open format of the free 7Zip program. It often achieves the best compression of the common formats, especially for large collections of documents, and supports strong AES 256 encryption. Like RAR, it usually needs extra software to open.
TAR, TAR.GZ, TAR.BZ2 and TAR.XZ
TAR comes from Unix and Linux. It bundles files without compressing them, preserving file permissions. Important for servers and software. It is usually combined with a compression method: GZ (fast), BZ2 (smaller) or XZ (smallest, slower). Developers and system administrators use these for backups and deployments.
ISO and CAB
ISO files are disk images, a complete copy of a CD, DVD or USB drive, used for operating system installers. CAB files are used by Windows installers and drivers.
Which format should you choose?
| Situation | Best format |
|---|---|
| Sending files to anyone | ZIP |
| Maximum compression for backups | 7Z or TAR.XZ |
| Linux servers and code | TAR.GZ or TAR.XZ |
| Encrypted sensitive files | 7Z (AES 256) or ZIP (AES) |
| Huge archives split for upload | 7Z or RAR multipart |
Opening archives without installing software
Everytoool’s Archive Converter reads ZIP, RAR, 7Z, TAR, GZ, BZ2, XZ, ISO, CAB and more directly in your browser. You can browse the contents, download individual files, or convert the whole archive to ZIP or TAR formats. Because it runs locally, the archive is never uploaded.
Some limitations apply to any browser based tool: encrypted RAR and 7Z archives and multipart archives need desktop software such as 7Zip or WinRAR.
Archive safety tips
- Be careful with archives from unknown senders. Archives are a common way to hide malicious programs. Do not open executable files (.exe.bat.js) from untrusted sources.
- Check file integrity. If a website publishes a checksum, compare it with a hash generator to make sure the download is genuine and complete.
- Use strong encryption for sensitive data. Choose AES encryption and a long, random password, and share the password through a different channel than the file.
- Keep backups. A single corrupted archive can lose many files at once; keep important backups in more than one place.
Archiving versus compressing individual files
Zipping a large PDF or video rarely makes it much smaller because it is already compressed. If size is the goal, compress the file itself. For example with Compress PDF or a video compressor. And then archive it if you need to bundle several files together.
Summary
- ZIP for compatibility, 7Z or TAR.XZ for maximum compression.
- RAR is common for downloads but needs extra software. Convert to ZIP for sharing.
- Archiving bundles files; real size savings come from compressible content.
- Treat archives from unknown sources with caution and verify checksums.