The Blazor Server templates create the initial files and directory structure for a Blazor Server app:
* If the `blazorserver` template is used, the app is populated with the following:
* Demonstration code for a `FetchData` component that loads data from a weather forecast service (`WeatherForecastService`) and user interaction with a `Counter` component.
*`Data` folder: Contains the `WeatherForecast` class and implementation of the `WeatherForecastService` that provides example weather data to the app's `FetchData` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app and the root Razor page of a Blazor Server app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following:
*`_Host.cshtml`: The root page of the app implemented as a Razor Page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The Host page specifies where the root `App` component (`App.razor`) is rendered.
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`Error` component (`Error.razor`): Rendered when an unhandled exception occurs in the app.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`Shared` folder: Contains the following shared components and stylesheets:
*`MainLayout` component (`MainLayout.razor`): The app's [layout component](xref:blazor/components/layouts).
*`MainLayout.razor.css`: Stylesheet for the app's main layout.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`NavMenu.razor.css`: Stylesheet for the app's navigation menu.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets.
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`appsettings.json` and environmental app settings files: Provide [configuration settings](xref:blazor/fundamentals/configuration) for the app.
*`Program.cs`: The app's entry point that sets up the ASP.NET Core [host](xref:fundamentals/host/generic-host) and contains the app's startup logic, including service registrations and request processing pipeline configuration:
* Specifies the app's [dependency injection (DI)](xref:fundamentals/dependency-injection) services. Services are added by calling <xref:Microsoft.Extensions.DependencyInjection.ComponentServiceCollectionExtensions.AddServerSideBlazor%2A>, and the `WeatherForecastService` is added to the service container for use by the example `FetchData` component.
*<xref:Microsoft.AspNetCore.Builder.ComponentEndpointRouteBuilderExtensions.MapBlazorHub%2A> is called to set up an endpoint for the real-time connection with the browser. The connection is created with [SignalR](xref:signalr/introduction), which is a framework for adding real-time web functionality to apps.
* [`MapFallbackToPage("/_Host")`](xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapFallbackToPage%2A) is called to set up the root page of the app (`Pages/_Host.cshtml`) and enable navigation.
Additional files and folders may appear in an app produced from a Blazor Server project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following components:
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`Shared` folder: Contains the following shared components and stylesheets:
*`MainLayout` component (`MainLayout.razor`): The app's [layout component](xref:blazor/components/layouts).
*`MainLayout.razor.css`: Stylesheet for the app's main layout.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`NavMenu.razor.css`: Stylesheet for the app's navigation menu.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets, including `appsettings.json` and environmental app settings files for [configuration settings](xref:blazor/fundamentals/configuration). The `index.html` webpage is the root page of the app implemented as an HTML page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The page specifies where the root `App` component is rendered. The component is rendered at the location of the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>`).
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`Program.cs`: The app's entry point that sets up the WebAssembly host:
* The `App` component is the root component of the app. The `App` component is specified as the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>` in `wwwroot/index.html`) to the root component collection (`builder.RootComponents.Add<App>("#app")`).
* [Services](xref:blazor/fundamentals/dependency-injection) are added and configured (for example, `builder.Services.AddSingleton<IMyDependency, MyDependency>()`).
Additional files and folders may appear in an app produced from a Blazor WebAssembly project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
To create an app that can run as either a Blazor Server app or a Blazor WebAssembly app, one approach is to place all of the app logic and components into a [Razor class library (RCL)](xref:blazor/components/class-libraries) and reference the RCL from separate Blazor Server and Blazor WebAssembly projects. For common services whose implementations differ based on the hosting model, define the service interfaces in the RCL and implement the services in the Blazor Server and Blazor WebAssembly projects.
The Blazor Server template creates the initial files and directory structure for a Blazor Server app. The app is populated with demonstration code for a `FetchData` component that loads data from a registered service, `WeatherForecastService`, and user interaction with a `Counter` component.
*`Data` folder: Contains the `WeatherForecast` class and implementation of the `WeatherForecastService` that provides example weather data to the app's `FetchData` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app and the root Razor page of a Blazor Server app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following:
*`_Host.cshtml`: The root page of the app implemented as a Razor Page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The Host page specifies where the root `App` component (`App.razor`) is rendered.
*`Shared` folder: Contains the following shared components and stylesheets:
*`MainLayout` component (`MainLayout.razor`): The app's [layout component](xref:blazor/components/layouts).
*`MainLayout.razor.css`: Stylesheet for the app's main layout.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`NavMenu.razor.css`: Stylesheet for the app's navigation menu.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets.
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`appsettings.json` and environmental app settings files: Provide [configuration settings](xref:blazor/fundamentals/configuration) for the app.
*`Program.cs`: The app's entry point that sets up the ASP.NET Core [host](xref:fundamentals/host/generic-host) and contains the app's startup logic, including service registrations and request processing pipeline configuration:
* Specifies the app's [dependency injection (DI)](xref:fundamentals/dependency-injection) services. Services are added by calling <xref:Microsoft.Extensions.DependencyInjection.ComponentServiceCollectionExtensions.AddServerSideBlazor%2A>, and the `WeatherForecastService` is added to the service container for use by the example `FetchData` component.
*<xref:Microsoft.AspNetCore.Builder.ComponentEndpointRouteBuilderExtensions.MapBlazorHub%2A> is called to set up an endpoint for the real-time connection with the browser. The connection is created with [SignalR](xref:signalr/introduction), which is a framework for adding real-time web functionality to apps.
* [`MapFallbackToPage("/_Host")`](xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapFallbackToPage%2A) is called to set up the root page of the app (`Pages/_Host.cshtml`) and enable navigation.
Additional files and folders may appear in an app produced from a Blazor Server project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
The Blazor WebAssembly template creates the initial files and directory structure for a Blazor WebAssembly app. The app is populated with demonstration code for a `FetchData` component that loads data from a static asset, `weather.json`, and user interaction with a `Counter` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following components:
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets, including `appsettings.json` and environmental app settings files for [configuration settings](xref:blazor/fundamentals/configuration). The `index.html` webpage is the root page of the app implemented as an HTML page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The page specifies where the root `App` component is rendered. The component is rendered at the location of the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>`).
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`Program.cs`: The app's entry point that sets up the WebAssembly host:
* The `App` component is the root component of the app. The `App` component is specified as the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>` in `wwwroot/index.html`) to the root component collection (`builder.RootComponents.Add<App>("#app")`).
* [Services](xref:blazor/fundamentals/dependency-injection) are added and configured (for example, `builder.Services.AddSingleton<IMyDependency, MyDependency>()`).
Additional files and folders may appear in an app produced from a Blazor WebAssembly project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
To create an app that can run as either a Blazor Server app or a Blazor WebAssembly app, one approach is to place all of the app logic and components into a [Razor class library (RCL)](xref:blazor/components/class-libraries) and reference the RCL from separate Blazor Server and Blazor WebAssembly projects. For common services whose implementations differ based on the hosting model, define the service interfaces in the RCL and implement the services in the Blazor Server and Blazor WebAssembly projects.
The Blazor Server template creates the initial files and directory structure for a Blazor Server app. The app is populated with demonstration code for a `FetchData` component that loads data from a registered service, `WeatherForecastService`, and user interaction with a `Counter` component.
*`Data` folder: Contains the `WeatherForecast` class and implementation of the `WeatherForecastService` that provides example weather data to the app's `FetchData` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app and the root Razor page of a Blazor Server app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following:
*`_Host.cshtml`: The root page of the app implemented as a Razor Page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The Host page specifies where the root `App` component (`App.razor`) is rendered.
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`Error` component (`Error.razor`): Rendered when an unhandled exception occurs in the app.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets.
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`appsettings.json` and environmental app settings files: Provide [configuration settings](xref:blazor/fundamentals/configuration) for the app.
*`Program.cs`: The app's entry point that sets up the ASP.NET Core [host](xref:fundamentals/host/generic-host).
*`Startup.cs`: Contains the app's startup logic. The `Startup` class defines two methods:
*`ConfigureServices`: Configures the app's [dependency injection (DI)](xref:fundamentals/dependency-injection) services. Services are added by calling <xref:Microsoft.Extensions.DependencyInjection.ComponentServiceCollectionExtensions.AddServerSideBlazor%2A>, and the `WeatherForecastService` is added to the service container for use by the example `FetchData` component.
*`Configure`: Configures the app's request handling pipeline:
*<xref:Microsoft.AspNetCore.Builder.ComponentEndpointRouteBuilderExtensions.MapBlazorHub%2A> is called to set up an endpoint for the real-time connection with the browser. The connection is created with [SignalR](xref:signalr/introduction), which is a framework for adding real-time web functionality to apps.
* [`MapFallbackToPage("/_Host")`](xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapFallbackToPage%2A) is called to set up the root page of the app (`Pages/_Host.cshtml`) and enable navigation.
Additional files and folders may appear in an app produced from a Blazor Server project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
The Blazor WebAssembly template creates the initial files and directory structure for a Blazor WebAssembly app. The app is populated with demonstration code for a `FetchData` component that loads data from a static asset, `weather.json`, and user interaction with a `Counter` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following components:
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets, including `appsettings.json` and environmental app settings files for [configuration settings](xref:blazor/fundamentals/configuration). The `index.html` webpage is the root page of the app implemented as an HTML page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The page specifies where the root `App` component is rendered. The component is rendered at the location of the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>`).
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`Program.cs`: The app's entry point that sets up the WebAssembly host:
* The `App` component is the root component of the app. The `App` component is specified as the `div` DOM element with an `id` of `app` (`<divid="app">Loading...</div>` in `wwwroot/index.html`) to the root component collection (`builder.RootComponents.Add<App>("#app")`).
* [Services](xref:blazor/fundamentals/dependency-injection) are added and configured (for example, `builder.Services.AddSingleton<IMyDependency, MyDependency>()`).
Additional files and folders may appear in an app produced from a Blazor WebAssembly project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
In Blazor Server apps, `<head>` content is located in the `Pages/_Host.cshtml` file.
In Blazor WebAssembly apps, `<head>` content is located in the `wwwroot/index.html` file.
## Dual Blazor Server/Blazor WebAssembly app
To create an app that can run as either a Blazor Server app or a Blazor WebAssembly app, one approach is to place all of the app logic and components into a [Razor class library (RCL)](xref:blazor/components/class-libraries) and reference the RCL from separate Blazor Server and Blazor WebAssembly projects. For common services whose implementations differ based on the hosting model, define the service interfaces in the RCL and implement the services in the Blazor Server and Blazor WebAssembly projects.
The Blazor Server template creates the initial files and directory structure for a Blazor Server app. The app is populated with demonstration code for a `FetchData` component that loads data from a registered service, `WeatherForecastService`, and user interaction with a `Counter` component.
*`Data` folder: Contains the `WeatherForecast` class and implementation of the `WeatherForecastService` that provides example weather data to the app's `FetchData` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app and the root Razor page of a Blazor Server app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following:
*`_Host.cshtml`: The root page of the app implemented as a Razor Page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The Host page specifies where the root `App` component (`App.razor`) is rendered.
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`Error` component (`Error.razor`): Rendered when an unhandled exception occurs in the app.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`MainLayout` component (`MainLayout.razor`): The app's [layout component](xref:blazor/components/layouts).
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets.
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`appsettings.json` and environmental app settings files: Provide [configuration settings](xref:blazor/fundamentals/configuration) for the app.
*`Startup.cs`: Contains the app's startup logic. The `Startup` class defines two methods:
*`ConfigureServices`: Configures the app's [dependency injection (DI)](xref:fundamentals/dependency-injection) services. Services are added by calling <xref:Microsoft.Extensions.DependencyInjection.ComponentServiceCollectionExtensions.AddServerSideBlazor%2A>, and the `WeatherForecastService` is added to the service container for use by the example `FetchData` component.
*`Configure`: Configures the app's request handling pipeline:
*<xref:Microsoft.AspNetCore.Builder.ComponentEndpointRouteBuilderExtensions.MapBlazorHub%2A> is called to set up an endpoint for the real-time connection with the browser. The connection is created with [SignalR](xref:signalr/introduction), which is a framework for adding real-time web functionality to apps.
* [`MapFallbackToPage("/_Host")`](xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapFallbackToPage%2A) is called to set up the root page of the app (`Pages/_Host.cshtml`) and enable navigation.
Additional files and folders may appear in an app produced from a Blazor Server project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
The Blazor WebAssembly template creates the initial files and directory structure for a Blazor WebAssembly app. The app is populated with demonstration code for a `FetchData` component that loads data from a static asset, `weather.json`, and user interaction with a `Counter` component.
*`Pages` folder: Contains the routable components/pages (`.razor`) that make up the Blazor app. The route for each page is specified using the [`@page`](xref:mvc/views/razor#page) directive. The template includes the following components:
*`Counter` component (`Counter.razor`): Implements the Counter page.
*`FetchData` component (`FetchData.razor`): Implements the Fetch data page.
*`Index` component (`Index.razor`): Implements the Home page.
*`MainLayout` component (`MainLayout.razor`): The app's [layout component](xref:blazor/components/layouts).
*`NavMenu` component (`NavMenu.razor`): Implements sidebar navigation. Includes the [`NavLink` component](xref:blazor/fundamentals/routing#navlink-and-navmenu-components) (<xref:Microsoft.AspNetCore.Components.Routing.NavLink>), which renders navigation links to other Razor components. The <xref:Microsoft.AspNetCore.Components.Routing.NavLink> component automatically indicates a selected state when its component is loaded, which helps the user understand which component is currently displayed.
*`wwwroot`: The [Web Root](xref:fundamentals/index#web-root) folder for the app containing the app's public static assets, including `appsettings.json` and environmental app settings files for [configuration settings](xref:blazor/fundamentals/configuration). The `index.html` webpage is the root page of the app implemented as an HTML page:
* When any page of the app is initially requested, this page is rendered and returned in the response.
* The page specifies where the root `App` component is rendered. The component is rendered at the location of the `app` DOM element (`<app>Loading...</app>`).
*`_Imports.razor`: Includes common Razor directives to include in the app's components (`.razor`), such as [`@using`](xref:mvc/views/razor#using) directives for namespaces.
*`App.razor`: The root component of the app that sets up client-side routing using the <xref:Microsoft.AspNetCore.Components.Routing.Router> component. The <xref:Microsoft.AspNetCore.Components.Routing.Router> component intercepts browser navigation and renders the page that matches the requested address.
*`Program.cs`: The app's entry point that sets up the WebAssembly host:
* The `App` component is the root component of the app. The `App` component is specified as the `app` DOM element (`<app>Loading...</app>` in `wwwroot/index.html`) to the root component collection (`builder.RootComponents.Add<App>("app")`).
* [Services](xref:blazor/fundamentals/dependency-injection) are added and configured (for example, `builder.Services.AddSingleton<IMyDependency, MyDependency>()`).
Additional files and folders may appear in an app produced from a Blazor WebAssembly project template when additional options are configured. For example, generating an app with ASP.NET Core Identity includes additional assets for authentication and authorization features.
## Location of `<head>` content
In Blazor Server apps, `<head>` content is located in the `Pages/_Host.cshtml` file.
In Blazor WebAssembly apps, `<head>` content is located in the `wwwroot/index.html` file.
To create an app that can run as either a Blazor Server app or a Blazor WebAssembly app, one approach is to place all of the app logic and components into a [Razor class library (RCL)](xref:blazor/components/class-libraries) and reference the RCL from separate Blazor Server and Blazor WebAssembly projects. For common services whose implementations differ based on the hosting model, define the service interfaces in the RCL and implement the services in the Blazor Server and Blazor WebAssembly projects.
