A Content Delivery Network or Content Submission Network, abbreviated to CDN, is a network of computers that can contain copies of information. Computers on the CDN can demand data they will not already have from other computers on the network that can then be delivered.

If, for example, someone wanted to do a live video transmitted from London who have visitors from worldwide planning to watch at the same time. This would put a massive load on the streaming server delivering the media, in this example a video stream. Picture if the viewers of this webcast wanted to watch from Australia, Brand new York, Los Angeles and Japan. The streaming storage space working in london would have to broadcast this live movie stream to all those locations which means the video streams would have to 'hop' many times before reaching their locations on the various regions. This compromises the rate of delivery and puts a massive load on the Video Streaming Server internet connection being employed by the streaming machine. In addition, it means the movie stream may experience 'packet corruption' or even 'packet loss' meaning the quality of the video being watched could be jeopardized. This is more relevant if the broadcast is using UDP. If the broadcast is being done over TCP there are more 'load' issues because there is a regular communication between server and client.

So the answer to this matter is to have a 'Point of origin' machine that takes the original video stream, which in turn moves it on to 'Point of presence' servers, or PoPs, around the world after request. So now our streaming server in London does not have to deliver to Australia, New York, Oregon and Japan as in our above example. A guest that would like to watch the video stream in Australia would use the same online player as people in London to watch the video, but now the player is looking at a CDN for a video stream rather than the single streaming storage space in London. The CDN would know from the requesting IP address that the request is coming from Australia and would request the video stream from a 'Point of presence' server nearest to Australia. If that flow does not exist, probably because it is not requested from this location before, the 'Point of presence' storage space would request it from the 'Origin server'. This process would be the same for the visitors in Nyc, Los Angeles and Japan.

The benefits of this are that the workload to broadcast the video stream is well balanced across many servers rather than just one. The bandwidth is also balanced because all the streams are not from the same source, which means more concurrent users can see the video stream with much greater stability. Almost all the CDN servers, the 'Point of origin' and the 'point of occurrence servers', are strategically located around the world on an internet backbone making the delivery speed between servers very fast and reliable.

Articles delivery networks are not bound to only sharing the load of movie and music streams. We are able to share images and PDF files in the same way. In fact any digital media can be requested over a CDN. We are not only restricted to media being distributed over a CDN, websites can be cached which obviously makes for faster delivery around the world. This will be significant for corporate websites that contain millions of hits.

Another good thing about by using a CDN is that once your digital media is on the 'Origin' servers or on the 'Point of presence' servers, it is effectively backed up. If the client requests data from your CDN server that is down, the CDN can produce a request to another storage space on the network and is still able deliver the media.

The last thing I would like to point out about using Articles Delivery Networks is that the 'Point of origin' servers can be your company's web servers in your company's server farm. They do not have to be a CDN server. This practice is not recommended by most CDN's as it is more likely to be your company's machine that is down or experiencing connection issues rather than a CDN storage space. The main one benefit of having your own 'Point of origin' server is it does allow you to maintain local backups of your content should you need to.