CDN (Content Delivery Network)

A CDN (Content Delivery Network) is a globally distributed set of servers that caches copies of your content close to your users. Requests are answered from a nearby edge location instead of traveling to your origin server, so pages load faster and your servers handle a fraction of the traffic.

In plain terms

It’s a chain of local warehouses in front of one central factory. A user in Singapore loading your site gets the images, scripts, and video from an edge server in Singapore, not from your origin in Virginia, cutting load time from seconds to milliseconds. The cloud versions are Amazon CloudFront, Azure Front Door, and Google Cloud CDN; independent networks like Cloudflare and Fastly work in front of any cloud.

Why it matters when you migrate

• It buys you regional freedom. With static content served from the edge, you can run your origin in one well-chosen region instead of many, which keeps the architecture simple and the bill smaller.
• It cuts your egress fees. CDN transfer is priced lower than raw data transfer out, and cached hits never touch the origin at all. High-traffic sites often save more on egress than the CDN costs.
• It absorbs the rough edges of cutover. During a migration, a CDN in front of file storage or the app shields the origin from traffic spikes and can keep serving cached content through a brief origin switch.