Content delivery network or in short CDN is a globally distributed proxy SERVER network that serves content from locations close by to the end-users. Usually, in websites, static files like HTML, CSS, JS files, images and videos are served from CDN.

Using CDN in delivering content helps to IMPROVE performance:

• Since users receive data from centres close to them as shown in the image below, they don't have to wait for long.

• Load on the servers is reduced significantly as some of the responsibility is shared by CDNs.

There are two types of CDNs, they are:

• Push CDNs: Here, the content is received by the CDNs whenever CHANGES occur on the server. The responsibility lies in us for uploading the content to CDNs. Content GETS updated to the CDN only when it is modified or added which in turn maximises storage by MINIMISING the traffic. Generally, sites with lesser traffic or content work well using push CDNs.
• Pull CDNs: Here new content is grabbed from the server when the first user requests the content from the site. This leads to slower requests for the first time till the content gets stored/cached on the CDN. These CDNs minimizes space utilized on CDN but can lead to redundant traffic when expired files are pulled before they are changed. Websites having heavy traffic work well when used with pull CDNs.