An Internal Developer Platform (IDP) is a self-service system that enables developers to deploy, monitor, and manage applications without touching infrastructure. Developers interact with a simple UI or API ("Deploy my app to production"). The IDP handles the complexity: containerization, Kubernetes orchestration, networking, secrets management, observability. Examples: Netlify (for static sites), Vercel (for Next.js), Airbnb's Shelton, or internal platforms built with Backstage.