Jeremy M. Kahn, MD Traditionally defined, telemedicine is the provision of medical care remotely by means of audiovisual technology. Using such technology, clinicians can examine patients and make treatment recommendations across long distances. Telemedicine is by no means a new concept—varieties such as tele radiology and telepathology that rely on “storeand-forward” techniques, in which images are captured and sent to a different location for later evaluation, have been around for more than 30 years. But technological advances including highresolution video cameras and stable broadband Internet have helped make real-time telemedicine an increasingly common mode of health care delivery in such diverse fields as dermatology, neurology, and intensive care. 1 The fact that in 2012 nearly half of US hospitals reported having active telemedicine programs indicates that telemedicine is now fully within the mainstream. 2 This dramatic expansion has profound implications for the health care system. Most important, telemedicine has the potential to substantially expand access to high-quality health care, overcoming not only geographic but also socioeconomic barriers to care. Just as neurologists can use telemedicine to treat a patient for stroke in the emergency department of a far-off rural hospital, primary care physicians can use it to treat nearby patients who have difficulty visiting a clinic, such as nursing home residents or patients with disabilities. In all these cases, telemedicine does more than just enable health care delivery across distances: it facilitates a kind of community-based care, improving access by making health care more convenient for both patients and providers.

Telemedicine also has the potential to substantially reduce health care costs. For providers, using telemedicine may be more efficient than seeing patients in brick-and-mortar offices, since it reduces the time and space needed to run a medical practice. For patients, telemedicine can reduce travel expenses and the opportunity costs associated with obtaining care, such as missed hours or days of work. For payers, it has the potential to reduce reimbursements because of reductions in overall utilization. For example, in the emergency-department setting, telemedicine may allow specialists in regional referral centers to remotely treat acutely ill patients