What is Cache?
TL;DR
Cache is temporary storage that saves frequently accessed data so it can be retrieved faster next time, like keeping a book on your desk instead of in the library.
Example
Types of cache:
Browser cache: Your browser saves images, CSS, JavaScript. Next visit, loads from local computer. Why sites load faster on repeat visits.
Server cache: Server saves processed results. Next request, skips processing. Database query took 2 seconds? Cache the result.
CDN cache: Content stored at edge servers. Users get content from nearest location.
How it works: First visit: Load image from server (500ms) Browser caches image. Second visit: Load from cache (5ms)
Cache hit vs. miss: Hit: Data found in cache. Fast. Miss: Data not in cache. Fetch from source.
Explanation
Cache Considerations
Freshness: How long before cache expires? Too short: Miss benefits of caching. Too long: Users see stale content.
Invalidation: When content changes, clear the cache. "There are only two hard things in computer science: cache invalidation and naming things."
Cache headers: Control caching via HTTP headers.
- Cache-Control: max-age=3600 (1 hour)
- ETag: Fingerprint for content
- Last-Modified: When content changed
Cache Strategy
| Content Type | Cache Duration |
|---|---|
| Static images | Long (1 year) |
| CSS/JS (versioned) | Long (1 year) |
| HTML pages | Short or no cache |
| API data | Depends on freshness needs |
Why It Matters
For Business Owners
Caching makes your site faster. Every millisecond matters. Faster sites have better conversion rates.
Caching reduces server costs. Fewer requests to your server means less computing power needed.
Caching can cause confusion. "I updated the page but still see old content" is usually a cache issue.
Caching strategy matters. Too aggressive = stale content. Too conservative = slow site.
When Users See Old Content
- Ask them to hard refresh (Ctrl+Shift+R)
- Check CDN cache settings
- Verify cache-busting for CSS/JS
- Clear server-side cache if applicable
Good cache configuration is part of good website development.
Need help with your digital project?
We build websites, apps, and digital solutions for businesses.
Get in touch