Web Development

Server Cache vs Browser Cache: What’s the Difference (and When to Clear Each)?

Server vs Browser Cache

Cache is one of those behind-the-scenes technologies that makes the modern internet feel fast. It’s also one of the most misunderstood. People hear “clear your cache” as a generic fix for everything—then worry it will delete files, break settings, or wipe their computer.

Let’s clear up the myths and explain caching in a practical way: what cache is, how it works, the key differences between server cache and browser cache, and what you should do as a user, business owner, or website manager when a page won’t update or loads incorrectly.

If you run a website (especially a WordPress site) or manage marketing campaigns, understanding cache can save you hours of frustration – because a lot of “my website is broken” issues are actually “the cache is doing exactly what it’s designed to do.”

What is a cache?

A cache is a temporary storage area that keeps copies of files or data so they can be accessed faster next time.

Instead of downloading or recreating the same resources over and over, your device, browser, or a server stores “known” items – then reuses them. That reduces:

Caching is basically a shortcut for performance: do the expensive work once, then reuse the result.

What kinds of things get cached?

What is a browser cache-Computing Australia Group

On a typical website, caching often involves:

images (logos, banners, product photos)
CSS files (styling)
JavaScript files (interactive features)
fonts
API responses (in some cases)
fully generated HTML pages (server-side page cache)
database query results (object cache)

Some cached data updates frequently, and some barely changes. The “art” (and risk) of caching is deciding what should be cached, for how long, and how it should be refreshed.

Cache myths

Myth: Clearing cache deletes my files.

No. Clearing browser cache removes temporary website files (and sometimes cookies if you choose them). It doesn’t delete your documents, photos, or apps.

Myth: Cache is always good.

Cache is great for speed – but it can cause confusion when a website updates and you’re still seeing older files.

Myth: Clearing cache “breaks” websites.

Usually the opposite: clearing cache forces a clean reload of the newest files.

Myth: Cache and cookies are the same thing.

They’re related but not identical. Cache stores website resources. Cookies store small pieces of information (like session/login state and preferences).

The two big categories: Server cache vs Browser cache

Here’s the simplest way to think about it:

Both aim to speed things up – but they do it in different places and for different reasons.

What is browser cache?

Browser cache is storage on a user’s device that keeps local copies of website files so the browser doesn’t need to download them every time.

For example, if you visit a site daily, the browser may cache:

So on your next visit, your browser loads many of those items instantly from your computer instead of requesting them again from the internet.

Where is browser cache stored?

Depending on the browser and device, it’s stored on:

Why browser cache matters

Browser caching can dramatically improve user experience:

It also reduces load on the website’s server—because fewer requests hit the origin.

Downsides of browser cache

Browser caching can occasionally cause:

display issues after a redesign (old CSS + new layout = broken formatting)
missing updates (you still see older images or scripts)
login issues if cookies/session data are involved (not always cache alone)
storage bloat over time, especially on low-storage devices

What is server cache?

Server cache refers to caching systems that happen on the website side – before content is sent to the user.

When a user requests a page, the server (or supporting layers) may serve a cached version instead of regenerating everything from scratch. This is crucial for:

Server caching improves speed by reducing expensive tasks like:

Server cache is an “umbrella term”

There are multiple server-side caching layers. The most common are:

1) Page cache (HTML cache)

Stores a fully generated HTML page so the server can deliver it quickly without rebuilding it each time. Great for blogs and marketing pages.

Stores results of common database queries or computed objects. This is huge for WordPress/WooCommerce – especially when paired with Redis or Memcached.

3) Opcode cache (e.g., OPcache for PHP)

PHP code normally needs to be compiled to bytecode. An opcode cache stores precompiled code so the server can execute it faster.

4) CDN cache (edge caching)

A Content Delivery Network (CDN) stores cached copies of assets (and sometimes pages) on servers around the world. Users are served content from the closest location, reducing latency.

5) Reverse proxy cache (e.g., Varnish, Nginx caching)

Sits in front of the application and caches responses, often very effectively for anonymous traffic.s.

6) Microcaching

Caches dynamic content for very short periods (like 1–10 seconds) to handle traffic spikes without serving stale content for long.

Why caching sometimes makes a website look “broken”

Caching is helpful, but it introduces one big challenge: cache invalidation—the process of ensuring cached content is updated at the right time.

A classic scenario:

Another common scenario:

Caching makes websites fast, but it also means changes aren’t always visible instantly unless caching is managed properly.

When should you clear cache?

Clearing cache is not something you need to do obsessively. But it is useful when troubleshooting.

Clear browser cache when:

a website layout looks wrong (missing styles, broken formatting)
images don’t update after a change
you’re stuck in a login loop
a site behaves differently on your device vs someone else’s
you’ve been asked to “hard refresh” by a developer

Purge server cache when:

a site update is live, but visitors still see the old version
you updated CSS/JS/images and changes don’t appear
your CDN is serving older assets
you changed menus/widgets/theme templates and the frontend is inconsistent
a performance plugin cache is still serving outdated pages

Will clearing cache delete saved passwords?

It depends on what you choose to delete.

Browsers usually separate:

If you select only cached images and files, your saved passwords typically remain.
If you also delete cookies/site data, you may be logged out of websites and may need to log in again.

Best practice: when troubleshooting, start by clearing cached images and files only.

Best practices for developers: caching without the headaches

Caching should be intentional. Here are proven practices to improve speed while reducing “why can’t I see my changes?” support tickets.

1) Use proper cache-control headers

Set clear caching rules for:

Static files often benefit from longer cache lifetimes, while HTML may need shorter lifetimes (or smart invalidation).

2) Don’t cache personalised pages (without rules)

Logged-in dashboards, carts, checkout pages, and account areas should usually bypass full-page caching or use careful variation rules.

3) Purge cache on update events

Good caching setups automatically purge relevant pages when:s

4) Use a layered approach

A practical stack often looks like:

Clearing cache: user-friendly explanation you can put on your website

If your audience includes non-technical users, add a short help section that explains:

This reduces support requests and makes troubleshooting smoother.

Once you’ve cleared your browser cache (andcookies/site data if needed), it’s a good idea to manually double-check that the information you wanted removed is actually gone. Yes, it takes a little extra time, but that quick verification can prevent cached data, saved form entries, or lingering sessions from being accessed later – especially on shared or recycled devices. If you’d like step-by-step help with device clean-up and data protection, reach out to our Perth team at helpdesk@computingaustralia.group.

Jargon Buster

Server – It is a system or computer that stores, processes and delivers webpages to users.

Content Delivery Network – a group of servers that are geographically distributed to provide faster internet content delivery.

PHP – A general-purpose scripting language used for web development.

Peter Machalski

FAQ

Does clearing browser cache speed up my computer?

Sometimes it can help free storage, but the bigger benefit is fixing website loading issues. Clearing cache too often may slow browsing temporarily because the browser has to re-download resources.

Why does my website look different on another device?

Different devices may have different cached versions of the site, different cookies, or even different DNS routing to CDNs. Testing in incognito and across devices helps isolate whether the issue is cache-related.

Is cache the same as cookies?

No. Cache stores website files (like images and scripts). Cookies store small data (like login sessions and preferences). Some browser “clear data” options wipe both, so read the checkbox labels carefully.

Can caching hurt SEO?

Caching itself doesn’t hurt SEO. In fact, faster sites often perform better. Problems happen when caching serves outdated or incorrect content to users or bots – especially if important pages are accidentally cached with the wrong version (rare, but possible with misconfiguration)..