We consider simple laser systems like a laser with modulated phase or modulated losses, a laser with injected signal and a laser with saturable absorber. It is well know that such dynamical systems are able to show chaotic behaviour in the intensity of the electromagnetic field. We demonstrate here experimentally and also theoretically that those systems may show also the existence of extreme events usually called optical rogue waves. We studied the physical origin of optical rogue waves in those systems. We point out the similarities and differences among them identifying the different mechanisms generating those extreme events. Finally we studied the capacity we have in predicting the appearance of optical rogue waves and the possible methods to control them. We show also a good qualitative agreement between experimental results and theoretical ones.