What is a cached page?
Caching is the web's habit of keeping a copy. A browser caches the images and scripts of a page so a return visit is faster. A CDN caches the whole page at servers close to the visitor so the origin does not have to build it every time. A search engine used to cache a page too: Google kept a snapshot of what it last crawled and showed it behind a "Cached" link in results, until it retired the feature in early 2024. Each copy is a frozen moment, and the trick of caching is knowing how long a moment should last.
The cached copy is what a visitor usually sees. The origin page is what you edited. The gap between them is where most "I updated the site and nothing changed" mysteries live.
Why it matters
Why a cached page matters
Speed and resilience. A page served from cache arrives in milliseconds, survives traffic spikes that would overwhelm the origin and, with the right setup, stays up when the origin is down. For a brand site with heavy imagery and film, caching at the edge is the difference between a launch page that holds under a campaign spike and one that returns a 502 to the audience you paid for.
Freshness is the trade. A cache that holds too long shows the old price, the old hero image, the campaign that ended last week. Search engines index what they fetch, so if the cached copy is stale, the index is too.
In practice
How a cached page works in practice
- 01
Caching is controlled by headers the server sends with each response: how long the copy may be kept (Cache-Control, max-age), a fingerprint for checking changes (ETag), and the date it last changed. Browsers and CDNs honor those rules, and a 304 Not Modified response is how the server confirms a copy is still good. Static assets such as logos and fonts get long lifetimes and versioned file names so a change forces a new download; HTML pages get short lifetimes or validation on every visit so edits appear promptly.
- 02
When you publish a change, purge. Managed hosting and CDNs offer a cache clear for a single URL or the whole site, and most content management systems trigger it automatically on save. If a client reports seeing the old version, the sequence is: purge the CDN, hard-refresh the browser, then check the origin directly to confirm the change is really there.
Watch out
What people get wrong about cached pages
Blaming the cache for everything and nothing. Some teams clear every cache on every edit, which throws away the speed benefit; others never clear it and wonder why the site is a week behind. The right setting is per file type, decided once. The other mistake is forgetting that Google's cached-page feature is gone: the way to see what Google holds for a URL now is the URL Inspection tool in Search Console, not a cache: search.
Caching personalized pages. A logged-in account page, a cart or anything that differs per visitor must be excluded from shared caches, or one visitor sees another's data. That is a security failure, not a speed trick.
