Edge Services
edge, edge computing, edge functions, edge workers, edge networkDefinition
Work done in the CDN's points of presence rather than at the origin — caching, TLS termination, redirects, rewrites, bot filtering, A/B splits, authentication checks, and increasingly small functions that run at whichever location the reader reached
The edge is defined by where it runs, not by what it does, and everything follows from the distance: it is close to the reader and far from the database. So the work that belongs there is work needing no state — decide, rewrite, allow, deny — and the work that does not is anything requiring a query. An edge function that calls back to a single-region database has moved the compute and kept the latency.
The part of your application that lives in a hundred cities. This site uses the plain half — Cloudflare doing DNS, the certificate, the cache and the firewall in front of a single-region origin.
Avoid: assuming the edge makes a page faster by itself. It removes distance. If the slow part is the render or the query, the reader is now waiting closer to home.