Cache
A cache stores a reusable copy of data so later requests can be served more quickly.
- Format
- Performance & CDN
- Updated
- Updated
Cache Aliases: caching, web cache.
Definition
A cache stores a reusable copy of data so later requests can be served more quickly.
How it works
Caches are everywhere on the web: your browser keeps one, CDNs are built on them, and DNS resolvers depend on them. Each follows rules about what to store and for how long — which is why a change you just published can take a while to show up. Somewhere along the way, an older copy simply has not expired yet.
Example: A browser can reuse a downloaded stylesheet instead of requesting it again on every page.
Often confused: A cache is a speed layer that can be emptied at any moment — never treat it as a backup.
Related terms
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Sources
Last reviewed 2026-07-19.