A CDN (Content Delivery Network) is a highly-distributed platform of servers that helps minimize delays in loading web page content by reducing the physical distance between the server and the user. This helps users around the world view the same high-quality content without slow loading times. Without a CDN, content origin servers must respond to every single end user request. This results in significant traffic to the origin and subsequent load, thereby increasing the chances for origin failure if the traffic spikes are exceedingly high or if the load is persistent.
By responding to end user requests in place of the origin and in closer physical and network proximity to the end user, a CDN offloads traffic from content servers and improves the web experience, thus benefiting both the content provider and its end users.