How does a form's data capture work?

I have this code to get data from a form:

@WebServlet(name = "computador", urlPatterns = {"/computador"})
public class computador extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        float total = Float.parseFloat(request.getParameter("total"));
        float preco = Float.parseFloat(request.getParameter("preco"));
        float consumo = Float.parseFloat(request.getParameter("consumo"));
    }

}

But I do not know why it uses request to get the data, instead of response . And what is response ?