Short for content delivery network or content distribution network, a CDN is a global network that caches static content (e.g., images, CSS, and videos) for a website around the world. CDN helps improve the load time of a website by loading the static content from the closest CDN server.
For example, someone in India visiting a web server in the United States must wait for each request to travel to and from the United States. Although each request may only be a few hundred milliseconds, a site that makes dozens of requests would increase the overall load time. However, a website utilizing a CDN could make some of the requests to a server closer to the visitor.
The picture above is an example of a user in India accessing a server in the United States. Then, they receive the static content (e.g., pictures) from a closer CDN.
Below is a listing of some of the companies who provide CDN solutions.