Transcranial Magnetic Stimulation (TMS) is one of the current and non-invasive neuromodulation techniques that can be used in the treatment of many mental illnesses. It works by using magnetic fields without causing seizures or loss of consciousness. It is based on the principle that the magnetic field created by a coil through which electric current passes creates a small, temporary electrical field in the nerve cells. In recent years, its use in the treatment of Major Depressive Disorder (MDD) has been increasing. The fact that 20-40% of MDD patients do not respond to antidepressants and psychotherapy interventions has led to the search for alternative treatment methods, such as TMS in the treatment of MDD. In this section, the history of TMS, its mechanism of action, application methods, and the place of TMS in the treatment of MDD will be discussed.