Every view in ASP.NET MVC is derived from the WebViewPage class. The following figure shows class hierarchy.

View class hierarchy

The Web.config file in the Views folder, indicates that the base type of every page is the System.Web.Mvc.WebViewPage as shown below:

Base type of razor view:
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    <pages pageBaseType="System.Web.Mvc.WebViewPage">
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Optimization"/>
        <add namespace="System.Web.Routing" />
        <add namespace="MVC_BasicTutorials" />

So, you can use any of the method and properties of WebViewPage and its base classes, such as WebPageBase, WebPageRenderingBase & WebPageExecutingBase, starting with the @ symbol.

The WebViewPage class includes following members.

Property Description
Ajax Gets or sets the AjaxHelper object that is used to render HTML using Ajax.
Html Gets or sets the HtmlHelper object that is used to render HTML elements.
Model Gets the Model property of the associated ViewDataDictionary object.
ViewBag Gets the view bag.
ViewContext Gets or sets the information that is used to render the view.
ViewData Gets or sets a dictionary that contains data to pass between the controller and the view.

Visit MSDN for detailed information on the WebViewPage members.

Thus, when you use the HtmlHelper class using @Html, you actually use the HtmlHelper class assigned to the Html property of WebViewPage.