What is cdn?

A CDN, or Content Delivery Network, is a group of servers located in different places around the world that store copies of a website’s files (like images, videos, scripts, and styles). When a visitor wants to view the site, the CDN serves those files from the server that is closest to the visitor, making the site load faster.

Let's break it down

  • Origin server - the main server where the website is originally hosted.
  • Edge servers - the many distributed servers in the CDN that cache copies of the site’s static files.
  • Caching - the process of storing a copy of a file on an edge server so it can be delivered quickly next time.
  • Request routing - when a user asks for a file, the CDN decides which edge server is nearest (or least busy) and sends the file from there.

Why does it matter?

  • Speed - shorter distance = less latency, so pages appear faster.
  • Reliability - if one edge server goes down, another can take over, keeping the site online.
  • Scalability - a CDN can handle huge traffic spikes without overloading the origin server.
  • Security - many CDNs add DDoS protection and hide the origin server’s IP address.

Where is it used?

  • Large e‑commerce sites (Amazon, Shopify stores) to deliver product images quickly.
  • Streaming platforms (Netflix, YouTube) to serve video chunks close to viewers.
  • News websites that experience sudden traffic surges during breaking stories.
  • Mobile apps that load assets (icons, fonts) from a CDN to improve performance.
  • Any website that wants faster load times for users around the globe.

Good things about it

  • Faster page load times improve user experience and SEO rankings.
  • Reduces load on the origin server, lowering hosting costs.
  • Provides built‑in protection against traffic spikes and some cyber attacks.
  • Easy to set up with many providers offering plug‑and‑play integrations.
  • Often includes analytics to see where traffic comes from and how files are performing.

Not-so-good things

  • Extra cost: premium CDN services can be pricey for high traffic volumes.
  • Complexity: configuring caching rules incorrectly can cause outdated content to be shown.
  • Dependency: if the CDN provider experiences an outage, your site may become inaccessible.
  • Limited control: some advanced customizations may not be possible on shared CDN platforms.
  • Privacy concerns: routing user data through third‑party servers may raise compliance issues.