How model is passed by browser to MVC controller action

I want to understand how a browser post request passes a model to an MVC controller action. I understand that the assembly of the form is sent by mail.

I don't understand how the entire view model is passed to the MVC controller over HTTP in a way that allows it to access the model objects.

[HttpPost]
public ActionResult PostDataExample(PostDataViewModel model)
{

    return Content(model.property1.ToString());

    **//How are we able to get above model from browser ?**
}