In layman terms, a Content Distribution Network or Content Delivery Network is a geographically distributed group of servers that works together to provide fast delivery of internet content.
Let's take for example when you surf Netflix content on your devices, what Netflix does is instead of delivering that content from the parent server/origin server they stream that content from a local server with respect to that location. Which decreases the load time and makes the website faster in general.
How does a CDN work?
The main objective of a CDN is to deliver content to the users at the fastest possible speeds.
The CDN servers are placed at Internet exchange points, these are the primary locations where different ISP (Internet Service Providers) connect in order to provide each other access to traffic originated on their different networks. As the CDN providers have connections to these high speed interconnected locations, it is able to reduce cost and transit times in high-speed data delivery.
How is CDN faster on loading websites?
Due to this globally distributed nature of CDN servers, the distance between the actual server and the user is reduced resulting in higher speeds, instead of connecting to the website's origin server, a CDN lets the user connect to the globally closest server. That is less distance or travel time which in turn means more speed.
In a Content Delivery Network, the load on the website is also divided between different servers resulting in a more efficient and reliable content streaming service
This also eliminates the issue of centralized failure, as there are multiple servers for the website, even if one fails by chance the other servers can quickly cache the information of the failed server thus having a negligible effect on the whole system.
In case there is more than usual traffic on a particular server, the system will route further traffic to another server, which increases the efficiency of the network.
To sum it up, CDN provides the user a more reliable, faster, and efficient method for content consuming by reducing latency. And significantly making the website faster rather than streaming everything from the origin server.