Transcranial magnetic stimulation (TMS) is a magnetic stimulation technology that uses time-varying magnetic field to induce induced currents in the cerebral cortex to change the action potential of cortical neurons, thereby affecting the metabolism and neural activity in the brain. TMS is a pain free, noninvasive, safe and reliable method of stimulating the central nervous system and peripheral nerve. TMS and functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), positron emission tomography (PET) and other new technologies are also known as "four brain science and technology in twenty-first Century".