hybris - Why do we use Model class (model.addAttribute()) in Spring MVC? -

i new hybris. uses spring mvc in controller classes see "model.addattribute("quantity", long.valueof(cartmodification.getquantityadded()))". whats reason of model class. why need use it. work httprequest/httpresponse objects.

this logic how can add information backend frontend. how spring mvc works. have here: spring mvc