Middleware runs before a request is completed (often at the edge) and is great for redirects, rewrites, and auth gating. Limitations: it runs in an Edge‑like runtime (no Node‑specific APIs), should be fast, and is not a place for heavy DB access.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "middleware-in-next.js:-what-is-it-good-for-and-w"
function explain() {
// Start from the core idea:
// Middleware runs before a request is completed (often at the edge) and is great for redirec
}