25 years ago, the first content delivery networks (CDNs) emerged, to solve a specific problem - how to make web pages load faster. More than two decades later, 72 percent of Internet content is delivered through CDNs. But the companies involved are still almost invisible - until something goes wrong. In 2021, in a series of outages, large numbers of unrelated websites all went out of action at the same time. It turned out that these sites had all come to rely on the same CDNs, effectively installing a single point of failure for large sections of the Internet.  Since then, large service providers have worked out how to avoid this problem - and one CDN provider told us in a podcast what to do when it does happen.  Major CDN players have extended into a distributed cloud role, running applications at the edge, and Cloudflare, for one, believes CDNs have a huge opportunity in "inference" - when AI pre-trained systems are deployed for actual applications. 2021 also saw the formation of the CDN Alliance, an industry body that aims to be a voice and forum for CDN players, along with the ecosystem that has grown up around them.  Mark de Jong, founder and chair of the CDN Alliance, tells us why CDNs need a voice, and what they need to be saying.