Point of Presence (PoP)

A point of presence is a physical location where a network terminates connections with the outside world: the place a client's request is answered and a record is handed over. In a delivery network the PoP is the final hop, and because it is the leg that crosses into someone else's infrastructure, it is usually the one that dominates the delivery half of end-to-end latency.

The reason it matters commercially is that clients do not all sit in one place. Serving every subscriber from a single region means most of them pay for a long haul on every record, and the ones on the wrong continent pay twice. Serving each from the nearest PoP makes the last hop short everywhere at once, without asking anyone to relocate their systems. Naming the serving PoP on each record is what turns the resulting latency claim into something a client can recompute instead of believe, which is the same logic that makes data provenance worth carrying.