They are responsible for passing data from controller to view.
ViewData:
1.It is a dictionary,which holds keys as strings.
2.It can be used to store any complex data.
3.They have to casted/Null check has to be made in view to avoid Error.
ViewBag:
1.They use dynamic property listed with C#4.0
2.They do not require type casting of complex objects.
/*Controller*/
public ActionResult Index()
{
ViewData["Sample"] = "Sample ViewData";
ViewBag.Hello = "Sample ViewBag";
return View();
}
They are accessed in view with respective Name declared in controller
/*View*/
@ViewBag.Hello
@ViewData["Sample"]
rangeshsripathi.com 