andard for defining data interchange formats on the Internet. 4G: - See Fourth-generation services. Fiber: - See Optical Fiber. First-generation services (1G): - Analog mobile phone services. Flat panel: - A thin display that use LCD, plasma, or other type of non-CRT technology. Fourth-generation services (4G): - Ultra-high-speed multimedia digital mobile phone services. Fractal: - An object that is self-similar at all scales, in which the final level of detail is never reached and never can be reached by increasing the scale at which observations are made. Fuel cell: - A device that converts a gas or liquid fuel into electricity to power a notebook computer, mobile phone, or other electronic product. Galileo: - A satellite-based radio navigation system currently under con- struction by the European Space Administration (ESA). GHz: - See Gigahertz. GIF: - See Graphics interchange format. Gigahertz (GHz): - One billion cycles per second. See Hertz. Global positioning system (GPS): - A satellite-based radio navigation system that allows users to find their precise location anywhere on earth. Global system for mobile communications (GSM): - A second-generation (2G) digital mobile phone technology based on TDMA that is the pre- dominant system in Europe and is gaining increasing popularity in North America. GLOSSARY GPS: - See Global positioning system. Graphical user interface (GUI): - A graphics-based user interface that features windows, icons and pointing device input. Graphics interchange format: - A popular graphics file format. GSM: - See Global System for Mobile Communications. GUI: - See Graphical User Interface. Haptic interface: - Communicating with a computer via touch sensation. Hertz (Hz): - The basic unit of electrical cycles. Hotpsot: - A place, such as a home or store, where a wireless connection is available. IEEE: - See Institute of Electrical and Electronics Engineers. ILEC: - See Incumbent Local Exchange Carrier. IP Telephony: - The two-way transmission of audio over a network that uses Internet 