A CDN (Content Delivery Network) is a distributed network of servers that deliver web content based on the geographic locations of users. CDNs cache static assets such as images, videos, stylesheets, and scripts on servers located closer to end users, reducing latency and improving load times. By distributing content across multiple servers, CDNs also enhance the reliability and scalability of web applications, reducing the load on the origin server and mitigating the impact of traffic spikes. Popular CDN providers include Cloudflare, Akamai, and Amazon CloudFront.