This review of spinal cord stimulation (SCS) and its technology begins with an overview of the history and background of electroanalgesia, from the use of electric fish in ancient times through the development of the first SCS devices. Discussion of the clinical goals of SCS as a treatment for neuropathic and ischemic pain includes accepted and emerging indications and focuses on various aspects of the technical goal of appropriate paresthesia coverage. While acknowledging that much remains to be discovered about the mechanisms of action of SCS, the review describes what is known about its neurochemical effects and summarizes the results of experimental and clinical studies that seek to illuminate why SCS is effective. After noting the importance and development of computer modeling studies that indicate ways to improve delivery of the electrical pulses, the review covers the advantages of various types of SCS electrodes and power generators and the use of computerized methods to optimize SCS therapy in individual patients and to provide information about the clinical performance of various types of equipment. Finally, this paper identifies important design issues and options as well as the challenges posed by various failure modes, by environmental and medical precautions, and by cost effectiveness and patient access issues.