Middleware
ASP.NET Core middleware pipeline β execution order, Use/Run/Map, and building custom middleware
Dependency Injection
Transient, Scoped, Singleton lifetimes, IServiceCollection, IServiceProvider, and circular dependency resolution
Routing & Controllers
Conventional vs attribute routing, ControllerBase, action results, model binding, and filters
Configuration
appsettings.json, environment variables, IOptions<T>, IOptionsSnapshot<T>, User Secrets, and environment-specific config
Minimal APIs
MapGet, MapPost, and comparison with Controller-based APIs in ASP.NET Core 6+