This chapter explores the specialized domain of invasive brain stimulation, with a particular emphasis on deep brain stimulation (DBS) as a groundbreaking technique in neuromodulation. It provides a detailed exploration of the mechanisms, applications, and potential of surgically implanted devices in treating severe neurological conditions unresponsive to less invasive methods. Historical perspectives trace DBS from its inception in the nineteenth century with the pioneering work of Fritsch and Hitzig, through its evolution driven by technological advances in neuroimaging and computational modeling. This chapter discusses the application of DBS to a variety of neurological and psychiatric disorders, emphasizing its role in Parkinson’s disease, and explores its expanding use in conditions like Alzheimer’s disease and major depression. Future prospects of DBS, including the development of closed-loop systems and the integration of machine learning for optimizing stimulation parameters, are also examined. This overview highlights the sophisticated integration of science, technology, and medicine in DBS and its significant impact on enhancing patient outcomes.