Fiber is a high-performance web framework for Go, inspired by Express.js (Node). It prioritizes speed and minimal boilerplate. A Fiber server can handle 1M+ requests per second on a single instance. It's built on fasthttp, a performance-focused HTTP library that differs from Go's standard net/http by reducing memory allocations and using efficient buffer reuse. Fiber handles routing, middleware, parameter binding, and templating. Its simplicity and speed make it ideal for microservices, APIs, and real-time backends where latency is critical.