Dynamical phase transitions are non-equilibrium phenomena characterised by the non-analytical behaviour of some physical quantity. These processes share many features with equilibrium transitions, first and foremost the concept of universality. A lot of interest has been attracted in recent years by a special class of dynamical transitions, called absorbing phase transitions. Many processes ranging from fluids percolating through a medium to the spread of epidemics can be studied in the framework of absorbing phase transitions. These systems exhibit a dynamical transition from an active phase, where the order parameter fluctuates around a non-zero value, to an inactive phase, where the system is trapped into an absorbing state with no activity at all.