Content delivery network (CDN) nodes are usually deployed in multiple geographically diverse locations connected to multiple internet backbone providers and local ISPs. Benefits include reducing bandwidth costs, improving page load times, or increasing global availability of content and in some cases offer DDoS (Distributed Denial of Service) protection. The number of nodes and servers making up a CDN varies, depending on the architecture, some reaching thousands of nodes with tens of thousands of servers on many remote points of presence (PoPs).
Requests for content are typically algorithmically directed to nodes that are optimal in some way. When optimizing for performance, locations that are best for serving content to the user may be chosen. This may be measured by choosing locations that are closest to the requesting client, or the highest availability in terms of server performance (both current and historical), so as to optimize delivery across local networks.
Most CDN providers will provide their services over a varying, defined, set of PoPs, depending on the coverage desired, such as United States, International or Global, Asia-Pacific, etc. These sets of PoPs can be called "edges", "edge nodes", "edge servers", or "edge networks" as they would be the closest edge of CDN assets to the end user. Most providers are subscription based services but some such as Cloudflare do offer some basic free entry level services to help protect and accelerate your website.