A Content Delivery Network (CDN) is a system of servers that work together to deliver internet[2] content quickly. This is done by strategically locating servers in various places around the world, some networks having thousands of them. These servers store popular content to speed up response times and balance the load of web traffic[1]. They also direct requests for content to the most efficient source. CDNs use specific protocols to provide access to content services, and some even allow clients to contribute resources. They also employ various security[3] measures to ensure the integrity of the content and protect user privacy[4]. However, they can potentially breach privacy regulations. The industry is evolving with new trends like streaming video traffic and emerging technologies like virtualization. CDNs are a key component in the delivery of internet services, and ongoing research is being conducted to optimize their performance.
A content delivery network or content distribution network (CDN) is a geographically distributed network of proxy servers and their data centers. The goal is to provide high availability and performance by distributing the service spatially relative to end users. CDNs came into existence in the late 1990s as a means for alleviating the performance bottlenecks of the Internet as the Internet was starting to become a mission-critical medium for people and enterprises. Since then, CDNs have grown to serve a large portion 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 media sites.
CDNs are a layer in the internet ecosystem. Content owners such as media companies and e-commerce vendors pay CDN operators to deliver their content to their end users. In turn, a CDN pays Internet service providers (ISPs), carriers, and network operators for hosting its servers in their data centers.
CDN is an umbrella term spanning different types of content delivery services: video streaming, software downloads, web and mobile content acceleration, licensed/managed CDN, transparent caching, and services to measure CDN performance, load balancing, Multi CDN switching and analytics and cloud intelligence. CDN vendors may cross over into other industries like security, DDoS protection and web application firewalls (WAF), and WAN optimization.