What is Viewbag in ASP.NET MVC

The ViewBag object is a wrapper on ViewData object. So you can access ViewData without data type converting in html.

Code example:

In controller

        public ActionResult Index()

        {

            ViewBag.TestName = "teststring";

            return View();

        }

In cshtml:

<h2>

   @ViewBag.TestName

   @ViewData["TestName"]

</h2>

   @ViewData["TestName"] is equal to  @ViewBag.TestName in here

Reference:

http://rachelappel.com/when-to-use-viewbag-viewdata-or-tempdata-in-asp.net-mvc-3-applications

You can use strong type data in html view by Viewbag.

It is a new feature in ASP.NET MVC 3 to pass data from Controllers to Views as same as ViewData.

But Viewbag is the dynamic type.

ViewData

<p>
    My name is
    <b><%: ViewData["name"] %></b>,
    <b><%: ViewData["age"] %></b> years old.
    <br />  
    I like the following colors:
</p>

ViewBag

<p>
    My name is
    <b><%: ViewBag.Name %></b>,
    <b><%: ViewBag.Age %></b> years old.
    <br />  
    I like the following colors:
</p>