Why CDNs?

A CDN like CloudFront has two purposes (as far as the context of this course is concerned):

Speed: Users get content from the server closest to them, which is faster than getting it from the origin server.
Security: The origin server is hidden from the public internet, and only the CDN can access it. This is a security measure that can help prevent DDoS attacks and other malicious activity.

Some CDNs, like CloudFlare, (not to be confused with CloudFront) are known for their incredibly robust security features. Things like DDoS protection, Web Application Firewalls, etc.

What Do CDNs Serve?

Images and videos are certainly common, but in reality any static asset is a good fit for a CDN. Here at Boot.dev, we use CloudFlare's CDN to serve the static assets for our frontend:

Images
HTML
CSS
JS

We deploy on their edge network, which means that our users get the initial HTML document quickly. That said, our backend server is a Go application running in a single region in the United States, so any dynamic requests to our API still have to come all the way back to the US.