What is CDN

A Content Delivery Network or Content Distribution Network (CDN) is a large distributed system of servers (called edge servers) deployed in multiple data centers across the Internet. CDNs have many points of presence (POPs) throughout the globe, which ultimately places the files closer to the end user to ensure the fastest delivery possible. They serve a large fraction of the Internet content today, including:
web objects (text, graphics and scripts), downloadable objects (media files, software, documents), applications (e-commerce, portals), live streaming media, on-demand streaming media, and social networks.

what is cdn

Content Delivery Networks distributes the content to multiple, geographically diverse nodes and then serves the content from whichever node is closest to the end-user, minimizing packet travel and increasing speed and efficiency.  Depending on traffic and number of nodes, the network's algorithms select the best routing options to deliver optimum performance and avoid bottlenecks.

Problems with excessive latency , as well as large variations in latency from moment to moment (which can cause annoying "jitter" in streaming audio and video), are minimized. The bandwidth each user "sees" is maximized. The difference is noticed most by users with high-speed Internet connections who often demand streaming content or large files.