Definition
Compression is the process of shrinking files so they take up less space and travel faster across the internet. Text files like HTML and CSS can be squeezed with methods such as gzip or Brotli, while images can be saved in lighter formats or at smaller sizes. The browser then unpacks them when the page loads.
Use Cases
Compression is used to speed up websites by sending smaller files, which is especially helpful on slow or mobile connections. It is applied to code, fonts, and images, often automatically by the server or a content delivery network.
Why It Matters for SEO
Compression matters for SEO because smaller files load faster, which lifts page speed and Core Web Vitals. Compressing and right-sizing images is a core part of image SEO, and trimming code speeds up HTML rendering. The savings are often large for very little effort.
Related Concepts
Related concepts include caching, image SEO, and minification. All of them reduce how much data a visitor has to download before a page is ready.