But how do various types of file-compression systems work — and why should you care?
Below is our selection of the most popular file compression types, how they work, and when you should use them.
What is File Compression?
File compression is a type of data compression. Personally, I find this efficient and a worthwhile space-saver; and file transfers take place MUCH more quickly. Two cases of compression are possible:
- Lossless Compression: It is possible to fully recover the input file.
- Lossy Compression: Some data gets thrown away so the file can be smaller — commonly used in media (images, audio, video).
Standard Compression Formats by File Types
ZIP & RAR (General Files – Lossless)
How it works: ZIP and RAR compress files by detecting patterns of duplication and redundancy in the data. Instead of "cat cat cat cat", it stores "4×cat".
Use Cases: Multiple file packaging, backups, software downloads.
Utilities: WinRAR, 7-Zip, Windows Explorer (ZIP).
JPEG (Images – Lossy)
How it works: JPEG throws away some details in the image that the human eye is less sensitive to, like small variations in color. It applies discrete cosine transformation on the image data.
Pros: Great size-to-quality ratio.
Cons: Repeated saves degrade quality.
Applications: Photography, web graphics, social media.
PNG (Images – Lossless)
How it works: PNG uses a technology called DEFLATE, which retains all the bits of an image but compresses them similarly to ZIP files.
Pros: Maintains original quality and supports transparency.
Cons: Larger than JPEG.
Use Cases: Web design, logos, icons, screenshots.
MP3 (Audio – Lossy)
How it works: MP3 compression removes sound frequencies most people can’t hear using psychoacoustic modeling to discard irrelevant information.
Use Cases: Streaming music, podcasts, mobile playback.
Alternatives: AAC, OGG.
FLAC (Audio – Lossless)
How it works: FLAC compresses audio without losing any sound data (lossless format), preserving every bit of the original recording.
Applications: High-quality audio archiving for audiophiles.
Pros: Picture-perfect quality, relatively small file size.
Cons: Larger than MP3.
MP4 & MOV (Video – Lossy)
How it works: These formats typically use video codecs like H.264 or H.265 which compress video by saving keyframes and predicting changes between them. They can also lower resolution and color depth.
MP4: Better compatibility, smaller file size.
MOV: Apple’s preferred format, great for editing.
Use Cases: Internet video, mobile video, professional video editing.
PDF (Documents – Mixed)
How it works: PDFs reduce size by compressing embedded images and fonts. Text uses lossless ZIP compression; images often use JPEG.
Use Cases: E-books, forms, brochures.
Tools: Adobe Acrobat, online compressors.
Lossless vs. Lossy: Quick Comparison
| Feature | Lossless Compression | Lossy Compression |
|---|---|---|
| Data Recovery | All recoverable | Some lost permanently |
| Apps | Text, documents, source code, PNG, FLAC | Images, audio, video |
| Examples | ZIP, PNG, FLAC | JPEG, MP3, MP4 |
| File Size | Larger | Smaller |
How to Compress Files
Here are a few of the most popular tools and techniques:
- For documents and standard files:
- Use built-in ZIP compression (Right-click > Compress/Zip)
- Use WinRAR or 7-Zip for more control
- Online tools:
- Websites like fileconvertz.com offer quick web-based conversions (e.g., WebP to JPG)
Conclusion
File compression has a whole lot more going for it than just reducing file sizes. Whether you’re archiving documents or sharing a video on social media, understanding how various kinds of compression function may enable you to get the most out of the format you use.
So next time you see .zip, .mp3, .mp4, or .jpeg, you’ll not only recognize the format — but also understand how it's working.