Problem Statement
What are the different caching layers in Next.js App Router?
Explanation
Next.js App Router has four caching mechanisms: Request Memoization deduplicates identical fetch requests in a single render pass, Data Cache stores fetch results across requests and deployments with configurable revalidation, Full Route Cache stores rendered HTML and RSC payload at build time for static routes, and Router Cache stores RSC payload in the browser for client-side navigation. Understanding these layers helps optimize performance by controlling what's cached where and for how long, with options to opt out of caching using cache no-store, revalidate 0, or dynamic functions like cookies() or headers().