A Content Delivery Network (CDN) is a system of distributed servers that work together to deliver web content to users more efficiently. By caching copies of content, such as images, videos, and web pages, across various locations, a CDN reduces the distance data must travel, leading to faster load times and improved performance for websites. CDNs also enhance reliability and security. They can handle large amounts of traffic and provide redundancy, ensuring that content remains accessible even during high demand or server failures. Additionally, CDNs often include security features, such as DDoS protection, to safeguard websites from malicious attacks.