What is a CDN?

On this page

Definition
Simple explanation
Why it matters
How it works
Real examples
Advantages
Limitations
Misunderstandings
Related terms
Used in reviews
FAQs
TTML perspective
Conclusion

Definition

A CDN is a geographically distributed network of servers that caches and serves website content from a location near the requesting user, reducing latency and load on the origin server.

Simple explanation

If your website's server is in London and a visitor is in Tokyo, every request has to travel a long physical distance, adding delay. A CDN keeps copies of your content on servers around the world, so that Tokyo visitor is served from a nearby server instead.

This matters most for static content — images, videos, scripts, stylesheets — that does not change per visitor and can safely be cached and reused.

Why it matters

Page load speed directly affects user experience, conversion rates and search ranking. A CDN is one of the highest-impact, lowest-effort ways to speed up a website for a global audience.

CDNs also absorb traffic spikes, since many requests are served from cached copies rather than hitting the origin server directly, which improves resilience during high-demand events.

How it works

1
Cache
The CDN stores copies of static files on servers around the world.
2
Route
A visitor's request is automatically directed to the nearest server.
3
Serve
That nearby server delivers the content, reducing travel distance and delay.
4
Refresh
Cached content is periodically updated or invalidated when the source changes.

Real examples

Products named for illustration only. Inclusion is not an endorsement.

Cloudflare
Widely used CDN with added security and performance features.
Amazon CloudFront
AWS's CDN, commonly paired with S3-hosted content.
Fastly
A CDN favoured for fine-grained caching control and edge computing.
Vercel Edge Network
Built-in CDN for websites and apps deployed on Vercel.

Advantages

Speeds up page loading for visitors far from the origin server.
Reduces load on the origin server by serving cached content instead.
Improves resilience during traffic spikes.
Many CDNs add security features like DDoS protection.

Limitations

Cached content can be temporarily stale after updates until it refreshes.
Adds another layer of infrastructure to configure and monitor.
Provides limited benefit for highly dynamic, personalised content.
Misconfigured caching rules can accidentally serve outdated or wrong content.

Common misunderstandings

Claim
A CDN replaces the need for a web server.
Reality
A CDN caches and delivers content faster, but an origin server is still needed to generate or store it.
Claim
CDNs only matter for huge, high-traffic websites.
Reality
Even small sites benefit from faster global load times and improved resilience.

Used in these reviews

CDN appears in these Tool Money Lab reviews. Handy if you want to see the concept in a real product context.

Frequently asked questions

Do I need a CDN for a small website?

It still helps with speed and resilience, and many CDNs offer generous free tiers for small sites.

Does a CDN improve SEO?

Indirectly, yes — faster page load times are a known ranking factor for search engines.

Can a CDN serve dynamic content?

Some modern CDNs support edge computing for limited dynamic logic, but they are primarily built for static content.

How does a CDN know which server is nearest?

It uses the visitor's network location to route the request to the closest available edge server.

Is a CDN the same as web hosting?

No, hosting stores and serves your site's original files; a CDN caches copies closer to visitors.

The Tool Money Lab perspective

A CDN is one of the few infrastructure upgrades that reliably improves both user experience and search visibility with minimal configuration effort.

When reviewing hosting and website-building tools, we treat built-in CDN support as a meaningful convenience, since bolting one on afterwards is more work than most non-technical users expect.

Conclusion

A CDN brings a website's content physically closer to its visitors, cutting load times and reducing strain on the origin server.

It is quiet, unglamorous infrastructure, but for any site with a geographically spread audience, it is one of the simplest performance wins available.