What Is Gzip Compression?
Gzip is a file compression algorithm used by web servers to reduce the size of HTML, CSS, JavaScript, and other text-based resources before sending them to the browser. It typically reduces file sizes by 60-80%, significantly improving page load times and reducing bandwidth usage.
How It Works
When a browser sends a request with the Accept-Encoding: gzip header, the server compresses the response using the gzip algorithm and sends it with Content-Encoding: gzip. The browser decompresses the response before rendering. This happens transparently without any user action.
Why It Matters
Enabling Gzip compression is one of the easiest and most impactful performance optimizations. It reduces data transfer, speeds up page loads, and improves Core Web Vitals. Most modern servers support Gzip; it just needs to be enabled.
Common Issues
- Gzip not enabled on the web server
- Only some file types compressed
- Double compression causing errors
- CDN not preserving Gzip encoding