What is Azure App Service?

Azure App Service is a fully managed PaaS for building, deploying, and scaling web applications and APIs. It supports multiple languages: .NET, Java, Node.js, Python, PHP, and containers. You deploy your code; Azure handles the OS, runtime patching, load balancing, and auto-scaling. Key features: Deployment slots (staging, production) for zero-downtime deployments and A/B testing. Auto-scaling based on CPU or schedule. Built-in CI/CD with GitHub, Azure DevOps. Custom domains and SSL. App Service Plans define the compute tier (Free, Shared, Basic, Standard, Premium). Multiple apps can share an App Service Plan, sharing the underlying compute resources.