Regularising QCD on a lattice is by now a well established tool to study the strong interaction in the low-energy regime where perturbation theory is not reliable anymore. Theoretical and algorithmic developments combined with facilities of large scale high performance computers induced significant progresses to explore the parameter space, even reaching the physical point: now, simulations are performed at the correct pion mass.
Those steps forward offer also the opportunity to solve difficult questions, either on old problems or on hot topics of the moment. After a brief presentation of the general state of the art, we will illustrate our statement by discussing cases of the strong coupling constant, g-2 anomaly of the muon and Delta I = 1/2 rule in K –> pi pi.
