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 Example: var builder = WebApplication.CreateBuilder(args); // Add services builder.Services.AddControllers(); builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); var app = builder.Build(); // Configure middleware if (app.Environment.IsDevelopment()) {     app.UseSwagger();     app.UseSwaggerUI(); } app.UseHttpsRedirection(); app.UseAuthorization(); app.MapControllers(); app.Run(); This file defines how the app starts , loads middleware, and sets up endpoints.

 Example default structure: MyFirstApi/ │   Program.cs │   MyFirstApi.csproj ├── Controllers/ │    WeatherForecastController.cs ├── Properties/ │    launchSettings.json ├── appsettings.json └── appsettings.Development.json Program.cs → Application startup configuration. Controllers/ → Contains API endpoints. appsettings.json → Configuration file. launchSettings.json → Environment and profile settings.

  Using Visual Studio: Open Visual Studio → "Create a new project". Select ASP.NET Core Web API . Configure project name & location. Choose .NET 8 (or latest) . Using Command Line: dotnet new webapi -n MyFirstApi cd MyFirstApi dotnet run

  Install .NET SDK Download from: https://dotnet.microsoft.com/download Verify installation: dotnet --version Choose an IDE Visual Studio (Windows/Mac) Best for beginners & large projects. Visual Studio Code (Cross-platform) Lightweight, flexible. Install C# extension.

 ASP.NET Core follows a middleware pipeline : Request → Middleware (Authentication, Logging, etc.) → Controller → Response Lightweight, modular design. Built-in dependency injection. Architecture Diagram: [Client] → [HTTP Server (Kestrel/IIS)] → [Middleware Pipeline] → [Controller] → [Data Access Layer] → [Database]

 ASP.NET Core offers: Cross-platform support (Windows, Linux, macOS). High performance (among the fastest web frameworks). Dependency Injection built-in . Unified MVC & API development model . Security (Authentication, Authorization, Data Protection). Integrated Swagger support for API documentation. Common Use Cases: E-commerce backend APIs. Mobile app data services. Microservices communication. Real-time services with SignalR.

1.  What is a Web API? 2.  Why Use ASP.NET Core for Web APIs?

A Web API (Application Programming Interface) is a set of endpoints exposed over the web that allow clients (like web apps, mobile apps, or other services) to interact with data or functionality. Different API Styles REST (Representational State Transfer) Uses HTTP methods (GET, POST, PUT, DELETE). Data is usually returned in JSON or XML . Example: GET /api/products Best for: Simple, stateless CRUD operations. SOAP (Simple Object Access Protocol) Uses XML-based messaging. Strict standards, more secure for enterprise needs. Example request: <soapenv:Envelope>     <soapenv:Body>         <getProductDetails>             <productId>123</productId>         </getProductDetails>     </soapenv:Body> </soapenv:Envelope> GraphQL Allows clients to request exactly the data they need. Single endpoint for all queries/mutations. E...