🔗 A complete guide to HTTP caching

Caching is the invisible backbone of the web. It’s what makes sites feel fast, reliable, and affordable to run. Done well, it slashes latency, reduces server load, and allows even fragile infrastructure to withstand sudden spikes in demand. Done poorly – or ignored entirely – it leaves websites slow, fragile, and expensive.

• The business case for caching
• Mental model: who caches what?
• Cache keys and variants
• Freshness vs validation
• Core HTTP caching headers
• Freshness &age calculations
• Common misconceptions &gotchas
• Patterns &recipes
• Beyond headers: browser behaviours
• CDNs in practice: Cloudflare
• Other caching layers in the stack
• Debugging &verification
• Caching in the AI-mediated web
• Wrapping up: caching as strategy