A content delivery network (CDN) refers to a geographically distributed group of servers that provide fast delivery of assets.
A CDN enables the quick transfer of Internet assets including HTML pages, Javascript files, Stylesheets, etc. Also, a properly configured CDN can help protect websites against some common malicious attacks, e.g. Distributed Denial of Service (DDOS) attacks.
A CDN does not host the actual web content, it caches content at the network edge to improve performance. Also, caching reduces hosting bandwidth to improve security.
Benefits of using a CDN:
Shorter loading times
Global distributed nature of a CDN means reduce distance between users and website sources.
A CDN is optimized for load balancing and better read performance
Smaller file size using minification and file compression methods
TLS/SSL certificates connection reuse and TLS false start enabled
Less bandwidth costs
Result is cached
Reduce routing distance from/to server
Better content availability and redundancy
Load balancing distributes network traffic to multiple servers