WordPress is a dynamic content management system for blogs, and many blog hosting providers offer free installations. It uses PHP and a database server, such as MySQL, to deliver dynamically-created posts. In other words, every time someone accesses some WordPress content, the data is called up from the database, processed, and displayed as an HTML page.
For sites that receive a high volume of visitors, all of the dynamic page creation, image loading, and content generation can be very resource-intensive. One solution web administrators use to lighten the load is a content delivery network (CDN). With a CDN, the blog loads certain data or media from its geographically dispersed servers rather than the web host’s server. Content delivery networks typically have multiple server locations to decrease proximity between the user and the content. They are also optimized to deliver the content quickly and seamlessly.
You can manually configure WordPress to use a CDN or rely on a plugin that will upload all images to the CDN rather than to your server. More advanced techniques include using a CDN for data retrieval or caching popular pages of a website remotely on the CDN.
Pricing models vary for content delivery networks, but most charge on a per-use basis. These prices are typically fairly low, which makes them an attractive alternative to paying high bandwidth costs for repeatedly-accessed static content hosted on your server.