Transcranial electrical stimulation or tES is a safe and non-invasive method, which involves the delivery of a very low intensity electric current on the scalp, through a battery-powered stimulator and two electrodes. Depending on the type of current delivered, it is called electrical stimulation with direct current (tDCS), alternating current (tACS) or random noise (tRNS). tES can modify the excitability state of the neurons affected by the current flow. The induced changes may persist beyond stimulation, for periods ranging from a few minutes to hours, depending on the parameters used. For this reason, tES shows a therapeutic potential similar to rTMS in the treatment of neurological and psychiatric disorders.