A PoP (point of presence) is a physical site - a data center or interconnection facility - where a CDN places edge servers near concentrations of viewers. The global mesh of PoPs is what lets a CDN serve content with low latency everywhere: a viewer is routed to a nearby PoP rather than a distant origin.
PoP density and placement (and good peering with local ISPs) directly determine performance in a region. When evaluating CDNs for global delivery, the map of PoPs and their connectivity in your key markets matters as much as headline price, because a sparse footprint in a target region means worse QoE there no matter how cheap the bytes are.
