Some stochastic PDEs are expected to be universal in the sense that they describe the macroscopic behaviour of a large class of microscopic statistical physics models. But the equations themsevles are ill-posed in the sense that they involve products of distributions, and hence the solutions are interpreted after suitable renormalisations by infinite quantities. We will use KPZ and \Phi^4_3 as two examples to explain the meanings are these infinities, and illustrate the universality features of these two equations.