Transcranial magnetic stimulation (TMS) is a form of non-invasive brain stimulation (NIBS) based on electromagnetic induction, first discovered by Michael Faraday in 1831. While early studies by Jacques-Arsène d’Arsonval explored magnetic brain stimulation in the 1890s, Anthony T. Barker developed the first modern TMS device in 1985, integrating concepts from Michael Polson’s magnetic peripheral nerve stimulation and P.A. Merton’s electrical cortical stimulation. By the 1990s, researchers such as Álvaro Pascual-Leone and Mark George helped establish TMS safety and its clinical application for depression. In 2008, the U.S. Food and Drug Administration (FDA) approved TMS for the major depressive disorder (MDD), with later approvals for presurgical mapping, migraine with aura, obsessive-compulsive disorder (OCD), smoking cessation, anxiety comorbid with MDD, and adolescent depression. Technological advancements, including functional magnetic resonance imaging (fMRI)-guided targeting, robot-assisted coil positioning, and accelerated protocols, are improving efficacy. This chapter traces TMS from its origins to modern applications, establishing a framework for exploring its ethical considerations, expanding clinical uses, and future directions in neuromodulation.