REST API Development in C# Full Stack refers to building stateless web services using ASP.NET Core Web API that allow frontend applications, mobile apps, and third-party systems to communicate with backend business logic through standard HTTP protocols. REST (Representational State Transfer) follows architectural principles such as: Stateless communication Resource-based endpoints Uniform interface Client-server architecture Cacheability A typical ASP.NET Core REST API consists of: Controllers Routing Dependency Injection Middleware Entity Framework Core Repository or Service Layer Authentication and Authorization Exception Handling Logging REST APIs commonly support HTTP methods: GET – Retrieve resources POST – Create resources PUT – Update resources PATCH – Partially update resources DELETE – Remove resources Modern REST APIs also implement: JWT (JSON Web Token) authentication OAuth 2.0 and OpenID Connect Swagger/OpenAPI documentation Model validation API versioning Pagination and filtering Asynchronous programming using async/await Secure communication over HTTPS In a C# Full Stack application, the REST API serves as the backend, while frontend frameworks such as Angular, React, Blazor, or ASP.NET Core MVC consume the API to deliver dynamic, scalable, and secure enterprise applications.