Browser Caching Explained
Browser caching tells a visitor's browser to keep a copy of files such as images, stylesheets and scripts on their device, so it does not re-download them on every page they view. The result is dramatically faster repeat visits.
Configured correctly, caching reduces load on your server and makes the whole site feel instant for returning users.
Why It Matters So Much
Caching is powerful because most visitors view more than one page, and many return later. Each cached file is one the browser never has to fetch again, so the savings compound across a whole session and across repeat visits over the following days.
What Visitors Notice
Done well, caching is invisible in the best way: returning visitors experience a site that feels instant, while you carry a lighter load on your server. The benefit grows with every repeat visit.
- Repeat visits feel almost instant.
- Navigating between pages is quicker.
- Your server handles more traffic comfortably.
- Updates still appear promptly when handled correctly.
Common Caching Pitfalls
Caching is a huge win, but configured carelessly it causes confusing problems — usually visitors seeing stale content long after you have updated it. Getting the rules right matters as much as turning caching on.
- Caching pages that should always be fresh, so updates do not show.
- Forgetting to rename changed files, so old versions stick around.
- Caching personalised content meant for one visitor.
- Setting times so short that the benefit disappears.
How It Works
When a browser first loads your site, it stores the unchanging files locally. On the next page or visit, it reuses those files instead of asking the server again.
The Updating Problem
Long caching is great until you publish a change and visitors still see the old version. We solve this with cache busting: changed files get a new name so browsers fetch them fresh, while unchanged files stay cached.
Our Approach
- Cache static assets for a long time to maximise speed.
- Rename files automatically whenever they change.
- Keep HTML pages on a shorter cache so content updates appear promptly.
If you need a hand with any of this, your Progressive Robot delivery team is ready to help. Raise a ticket from the Support area of your client portal or speak to your account manager and we will guide you through the next steps.