TMS stands for transcranial magnetic stimulation. It is used to treat depression by stimulating the brain using electromagnetic fields, similar to those produced by an MRI machine. TMS is non-invasive, meaning that it does not involve surgery. It does not require any anesthesia or sedation, as the patient remains awake and alert during the treatment. TMS is also non-systemic, meaning that it is not taken by mouth and does not circulate in the blood stream, limiting its side effects.