A Content Delivery Network (CDN) is a system of distributed servers that deliver web content to users based on their geographic location. By caching content closer to users, CDNs reduce latency and improve load times, enhancing the overall user experience. CDNs are essential for websites with high traffic or global reach, as they help manage bandwidth and ensure reliability. They also provide security features, such as DDoS protection, making them a vital component of modern web architecture.