Transcranial Magnetic Stimulation is a noninvasive treatment for major depressive disorder that uses magnetic pulses to stimulate underactive brain regions involved in mood regulation, typically the left dorsolateral prefrontal cortex. It is FDA-approved for adults with treatment-resistant depression and has recently been cleared for adolescents aged 15–21. Treatments are delivered 5 days per week for 4–6 weeks, with each session lasting 20–40 minutes (or as short as 3 minutes with theta-burst protocols). TMS has a response rate of about 50–60% and a remission rate of 30–40%, offering an effective alternative when medications fail. Side effects are generally mild, including scalp discomfort and transient headaches, with no need for anesthesia or recovery time.