What are Action Methods in ASP.NET Core Web APIs?

Action Methods are methods in ASP.NET Core controllers that handle incoming HTTP requests and implement the API's business operations. For example, a controller might expose methods for: Getting customers Creating an order Updating a product Deleting a record HTTP attributes such as [HttpGet], [HttpPost], [HttpPut], and [HttpDelete] are commonly used to map requests to appropriate action methods. A simplified example is: [HttpGet("{id}")] public async Task GetCustomer(int id) { var customer = await service.GetCustomerAsync(id); if (customer == null) return NotFound(); return Ok(customer); } Here, the action method receives the HTTP request, invokes the appropriate application/service logic, and returns an HTTP response. In enterprise applications, action methods should generally remain thin. They should handle HTTP-specific concerns such as model binding, validation, status codes, and authorization while delegating business logic to application or domain services. This approach improves: Maintainability Testability Separation of concerns Reusability API consistency Action methods therefore form an important boundary between the HTTP layer and the application's business logic, rather than being a place to put all business rules and database operations.