Fastly VCL
Fastly VCL (Varnish Configuration Language) is a domain-specific language used to configure Fastly's edge cloud platform for content delivery, caching, and security. It allows developers to write custom logic that controls how HTTP requests and responses are handled at the edge, enabling real-time modifications, caching rules, and traffic routing. VCL is based on the Varnish Cache project but extended with Fastly-specific features for their global network.
Developers should learn Fastly VCL when building or optimizing web applications that require high-performance content delivery, advanced caching strategies, or custom edge logic for security and personalization. It's essential for use cases like A/B testing, bot mitigation, geo-blocking, and dynamic content assembly at the edge, particularly in e-commerce, media streaming, and SaaS platforms where low latency and scalability are critical.