MVC ViewBag, ViewData, or TempData

ViewData

• ViewData is a dictionary object that you put data into, which then becomes available to the view. ViewData is a derivative of the ViewDataDictionary class, so you can access by the familiar "key/value" syntax.

ViewBag

• The ViewBag object is a wrapper around the ViewData object that allows you to create dynamic properties for the ViewBag.(Dynamic mean variable type define in reun time ex var)
• 
  

TempData object works well in one basic scenario:

• Passing data between the current and next HTTP requests (Data between one request to another)

public class HomeController : Controller

{

    // ViewBag & ViewData sample

    public ActionResult Index()

    {

        var featuredProduct = new Product

        {

            Name = "Special Cupcake Assortment!",

            Description = "Delectable vanilla and chocolate cupcakes",

            CreationDate = DateTime.Today,

            ExpirationDate = DateTime.Today.AddDays(7),

            ImageName = "cupcakes.jpg",

            Price = 5.99M,

            QtyOnHand = 12

        };

        ViewData["FeaturedProduct"] = featuredProduct;

        ViewBag.Product = featuredProduct;

        TempData["FeaturedProduct"] = featuredProduct;  

        return View();

    }

}

<div>

    <a href="/Products">

    <img src='@Url.Content("\\Content\\Images\\cake.jpg")' alt="Fourth Coffee Bakery"/>    

    </a>

    <div>

        Today's Featured Product is!

        <br />

        <h4>@ViewBag.FeaturedProduct.Name</h4>

        <h3>@viewDataProduct.Name</h3>

        <h2>@tempDataProduct.Name</h2>

    </div>

    @Html.ActionLink("Test Tempdata","Featured")

</div>

Temp Data

    TempData["FeaturedProduct"] = featuredProduct;

    //After the redirect, the ViewBag & ViewData objects are no longer available

    //Only TempData survives a redirect

    return new RedirectResult(@"~\Featured\");

@using FourthCoffee.Models;
@model FourthCoffee.Models.Product
@{
    ViewBag.Title = "Details";
    var featuredProduct = TempData["FeaturedProduct"] as Product;
}


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