A content delivery network (CDN) is a collection of web servers distributed across multiple locations to deliver content more efficiently to users.
Some large Internet companies own their own CDN, but it’s cost-effective to use a CDN service provider, such as Akamai Technologies, Mirror Image Internet, or Limelight Networks.
For start-up companies and private web sites, the cost of a CDN service can be prohibitive, but as your target audience grows larger and becomes more global, a CDN is necessary to achieve fast response times.