How data getting pass from controller to view?

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MVC4

I have experience in mvc 3.5 but still i have confusion
suppose,

[HttpGet]
       public ActionResult Index()
       {
           Employee employee = new Employee();

           return View(employee);
       }

we have method Index, it passes class employee which has static constructor we are initiating values of object employee

but same data i can able to fetch from
@Model properties or
@model Employee or
@ViewData.Model

same cannot be get by ViewBag

so is it like when we pass data Action to View it store data in ViewData memory somewhere,how this happening internally want to know.
can we fetch from ViewBag

What I have tried:

Question relative mvc data flowing