A CDN (Content Delivery Network) is a network of servers that are geographically distributed and provide content such as images, videos, audio files and other static or dynamic content. The aim of the CDN is to improve the speed and availability of content by serving users' requests from a server close to their location. This reduces latency and increases the performance of the website or application. A CDN is often used by companies that have a global presence or need to share content with many users to ensure a better user experience.