The primary purpose of a content delivery network (CDN) is to improve the performance and availability of web content by distributing it across multiple servers located in various geographical locations. CDNs reduce latency by serving content from the nearest server to the user, leading to faster load times and a better user experience. They also enhance scalability and provide a layer of security against Distributed Denial of Service (DDoS) attacks. Popular CDN providers include Akamai and Cloudflare, vital for high-traffic websites.