Definition
Browser caching allows the browser to store local copies of web resources (images, CSS, JS, fonts) during the first visit. On subsequent visits, the browser uses these local copies instead of re-downloading them, speeding up load time. Caching is controlled via HTTP headers like Cache-Control, Expires, and ETag. A good caching strategy can reduce load time by 50% or more for returning visitors. Best practices include setting long cache durations for static resources, using versioned file names (cache busting) to force updates, and distinguishing between public and private cache based on data sensitivity. For SEO, well-configured caching improves Core Web Vitals, particularly LCP and FCP.
Key Points
- Reduces load time for returning visitors
- Controlled via HTTP headers: Cache-Control, Expires, ETag
- Requires a cache busting strategy for updates
Practical Examples
Cache-Control configuration
A site sets Cache-Control: max-age=31536000 for its versioned CSS and JS files, keeping them cached for one year.
Cache busting
After a design update, a hash is added to the CSS filename (style.abc123.css) to force downloading the new version.
Frequently Asked Questions
Indirectly yes. Good caching improves user experience. Google recommends it in its PageSpeed Insights audits.
Configure Cache-Control headers on your server (Apache, Nginx). Set long durations for versioned static resources.
Go Further with LemmiLink
Discover how LemmiLink can help you put these SEO concepts into practice.
Last updated: 2026-02-07