When a user is not authorized to access a specific action, ASP.NET Core returns a default HTTP status code of 401 Unauthorized. This status code indicates that the request lacks proper authentication credentials or the provided credentials are invalid for the requested resource. It's a fundamental part of the authentication and authorization process in web applications.

The "Shared" folder in an ASP.NET Core MVC project typically contains the shared Razor views like layout and error pages. These views can be reused across multiple pages, providing a consistent look and feel to the application.

ASP.NET Core uses antiforgery tokens to protect against cross-site request forgery (CSRF) attacks. These tokens are generated and validated to ensure that a request originates from a trusted source. Session cookies, basic authentication, and SSL certificates address other security concerns but are not specific safeguards against CSRF attacks.

A common reason for integrating ASP.NET Core Identity into a web application is centralized user management. It allows the application to have a unified system for managing user accounts, roles, and permissions. This simplifies user authentication, authorization, and user data management, making it easier for teams to maintain and secure the application.

The purpose of the asp-for attribute in a Razor form input field is to associate the input field with a model property. It creates a binding between the input field and the model property, allowing automatic data binding when the form is submitted. This attribute is essential for model binding in ASP.NET Core, ensuring that form data is correctly mapped to model properties.

To update identity-related configurations at runtime, you should use IOptionsMonitor. This allows for dynamic configuration changes without requiring a server restart, making it suitable for scenarios where runtime updates are essential.

In ASP.NET Core, the NotFound action result is used to represent a situation where the requested resource is not found. It returns an HTTP 404 status code, indicating that the resource could not be located. This is the appropriate response for this scenario.

To capture the product's id from a URL like /products/5, you can use the route template /products/{id}. The {id} segment is a placeholder for the product's id, and the :int constraint ensures that it must be an integer value. This allows you to retrieve and process the id as a parameter in your controller action.

Integration testing concentrates on testing multiple components of an application together. It ensures that these components work correctly when combined and can communicate effectively. It's an essential step between unit testing and system testing in the testing life cycle.

The recommended approach for API versioning in ASP.NET Core is to embed the API version in the route URL. This approach is commonly referred to as "URI versioning" and provides clear versioning information within the request URL, making it easy for developers and clients to understand and use different API versions.

The [Authorize] attribute should be applied above the method that requires authorization. This means you place it directly above the action method within a controller where you want to restrict access. This approach allows for fine-grained control over which actions are protected and who can access them, ensuring security at the method level.

To get started with ASP.NET Core development, the primary software you need to install is the .NET SDK (Software Development Kit). This kit includes the necessary tools, libraries, and runtime environments to build, test, and run ASP.NET Core applications. Visual Studio Code is a popular code editor but does not include all the components required for ASP.NET Core development.