A number of working definitions for Telemedicine, Telehealth, Telecare, eHealth, and Health Telematics have been provided by a variety of sources [1, 2, 3, 7, 17, 23, 24, 26, 27, 28, 32, 33, 36, 37, 45, 48, 54]:

• “Telemedicine is the use of telecommunication technologies to provide healthcare services across geographic, temporal, social, and cultural barriers” (J. Reid, 1996);
• “The use of electronic com­mu­nication and information technologies to provide or support clinical care at a distance” (U.S. Department of Commerce, 1997) [23];
• “The delivery of healthcare services, where distance is a critical factor, by healthcare professionals using information and communications technolo­gies for the exchange of valid information for diagnosis, treatment and prevention of disease and inju­ries, research and evaluation, and for the continuing education of healthcare providers, all in the interest of advancing the health of individuals and their communities” (WHO, 1997) [5, 6];
• “The investigation, monitoring and management of patients, using systems which allow ready access to expert advice and to patient information, no matter where the patient or relevant information is located” (EU 2004) [32];
• “The provision of healthcare services, through use of ICT, in situations where the health pro­fessional and the patient (or two health professionals) are not in the same location” (EU, 2008) [33].

Telehealth although sometimes interchangeably used with Telemedicine, is generally a broader term, covering, besides clinical (practical) applications, also various aspects of distant medical edu­cation, web-based patients’ records and information exchange:

• “The application of info­rmation and communications technologies across the whole range of functions that affect the health sector” (EU, 2004) [32];
• “The use of electronic information and telecommunication techno­logies to support long-distance clinical health care, patient and professional health-related edu­cation, public health, and health administration“ (U.S. Department of Health and Human Servi­ces, 2001) [24];
• “The integration of telecommunications systems into the practice of protecting and promoting health in the field of public health” (WHO, 1998) [5, 6].

Telecare is somewhat different term, related equally to the domain of social care, as well as to the health care. It commonly covers a spectrum of ICT-based applications and services using remote data transfer and control, aimed at facilitating independent living of the elderly and vulnerable individuals, ranging from household appliances to health data monitoring.

Health Telematics is defined as follows:

• “A composite term for health-related activities, services and systems, carried out over a distance by means of information and communications technologies, for the purposes of global health promotion, disease control, and healthcare, as well as education, management, and research for health” (WHO, 1998) [5, 6];

• “The combined use of informatics and telecommunications as applied to health delivery” (G7 Information Society Initiative, 1999).

It consists of 4 areas: telemedicine, tele-education for health, telematics for health research, and telematics for health services management.

The concept of eHealth has recently emerged and is increasingly used today as an ultimate “umbrella” term to encompass various Telemedicine and Telehealth activities, together with electronic health data administration [54].

• eHealth is an emerging field in the intersection of medical informatics, public health and business, referring to health services and information delivered or enhanced through the Internet and related technologies. In a broader sense, the term characterises a technical development, but also a state-of-mind, a way of thinking, an attitude, and a commitment for networked, global thinking, to improve healthcare locally, regionally, and worldwide by using information and communication technology. (Journal of Medical Internet Research, 2001);

• eHealth refers to the use of modern information and communication technologies to meet needs of citizens, patients, healthcare professionals, healthcare providers, as well as policy makers. (Ministerial Declaration, eHealth, 22 May 2003);

• eHealth refers to the use of information and communications techniques including health-related activities, services and systems carried out over a distance for the purposes of global health promotion, disease control and healthcare, as well as education, management and research for health. (L. Androuchko, ITU-D, ITU Workshop on Standardisation on eHealth, 2003);

• eHealth is the combined use in the health sector of electronic communication and information technology (digital data transmitted, stored and retrieved electronically) for clinical, education and administrative purposes, both at the local site and at a distance (World Health Organization, 2004) [8].

he Diagram shows schematically relationship between the above described concepts [Courtesy European Space Agency; with permission].