#caching

Caching is the oldest trick in computing: store an expensive result once, hand it back cheaply forever after. It lives in your CPU, your browser, the CDN, and your database. Here is how it works and when it quietly becomes a liability.

Next.js 16 flipped the caching default: nothing is cached unless you write 'use cache'. That sounds like a footgun and turns out to be the fix. Here's the mental model that makes Partial Prerendering click, and the traps that hang your build for 50 seconds.

A CDN puts copies of your content on servers near your users so the bytes travel a short distance instead of crossing an ocean every request. The thing most people miss: the bottleneck usually isn't bandwidth, it's latency, and latency is bounded by the speed of light.

DNS is the internet's phonebook, but that analogy hides the interesting part: a global lookup system, distributed across millions of servers, that resolves a name in tens of milliseconds and quietly holds the whole web together.