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Performance

Caching

Cache | Browser Cache

Portrait of Lukas Horvath, co-founder of Roelu Studio
Lukas HorvathCo-founder

What is Caching?

Caching is the practice of storing a copy of content or data temporarily so it can be served faster on subsequent requests. On the web, caching happens at multiple layers: in the visitor's browser (browser cache), at the CDN edge, at the server, and inside databases. Each layer reduces the work needed to deliver a page. Common cache types include browser cache, CDN cache, application cache, and database query cache.

Why it matters

Caching is the difference between a site that scales and a site that buckles. Without it, every visitor triggers the full computation — query the database, render the template, package the assets, ship them down the wire — for content that hasn't changed in days. With it, that work happens once and the result is served thousands of times in milliseconds. The trade-off is freshness: cached content can go stale if invalidation rules are sloppy. The teams who get this right ship fast sites that handle traffic spikes without breaking a sweat. The teams who don't end up paying for bigger servers to do the same work over and over.

How it works

When a browser requests a page, it first checks its own cache for a recent copy. If none, the request travels to the CDN, which checks its edge cache. If none there, the request hits the origin server, which might check an application cache or a Redis store before regenerating the page from the database. Each layer sets cache headers — like Cache-Control and ETag — telling the next layer how long to hold the content and when to revalidate. Smart caching on a modern stack means most page requests never reach the origin at all. Marketing publishes an update, the CDN invalidates the old version, the new version starts caching globally within seconds.

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