title: Personal medical data in public networks.
abstract: The Internet is a global mesh of countless computers and computer networks that are connected by glass-fibre lines, copper cables or via satellites, and which can communicate with each other. In principle, any computer, whether Macintosh, IBM-compatible PC or supercomputer, and regardless of the operation system and user software installed, may be connected to the Internet. To enable data exchange between the various computers and network systems, standardized procedures, 'protocols', have been developed. Major protocols are IP (Internet protocol) and TCP (transmission control protocol), which is based on the former. Apart from the Internet, there are other computer networks, e.g. videotext or AOL. Within these networks, communication is controlled by other protocols. When data are exchanged between these various networks, they have to pass a 'gateway', i.e. a source computer. Any file stored on an Internet computer is given an unambiguous address worldwide, the universal resource localizer (URL). The URL consists of the transmission protocol, e.g. http:, followed by the computer address, e.g. www.web.de or www.fzk.de and the path and name of the file, e.g. start.htm. This paper presents a brief historical survey of the Internet, including a description of its general function. It then deals with the topic of patient data on the Internet, the general safety of the Internet, and the function of search machines. The benefits to the user will thus be illustrated.