The spread (or propagation) of a disturbance in matter or in a vacuum, in space and in time.  The wave is characterized by frequency, wavelength, propagation rate and amplitude.

The distance between two successive peaks of a wave, measured in units of length, such as meter (m), centimeter (cm), millimeter (mm), micron (µm), nanometer (nm) and Ångstrom (Å).

See Wireless Internet.

A wireless communications network (e.g. Wi-Fi) that uses radio waves to transmit information and data back and forth among different end-user devices (such as mobile phones, tablets or smart phones).  

A branch of the United Nations Organization dealing with health.  Among its main roles:  acting as leader on the subject of world health, determining priorities for health research, setting norms and standards (international), elaborating policy, providing support for countries throughout the world, supervising and assessing health trends.

The basic unit of any element, comprising a nucleus and a cloud of electrons surrounding it.  Electrons are negatively charged, and the nucleus is positively charged.  The nucleus is composed of neutrons (no electric charge) and protons (positively charged).  The electrons are attached to the nucleus by means of electromagnetic power.  The atoms composing matter are attached to each other by chemical bonds to form molecules.

A device that constitutes an interface between an electric circuit and space, and serves to transmit and receive electromagnetic waves. It is generally made of metal and is capable of converting an electric current into electromagnetic radiation and vice versa.

One of the physical measures which characterizes electromagnetic radiation. The "height" or amplitude of a wave describes the intensity of the fields (electric and magnetic) of radiation.

A malignant progressive disease of blood cells. There are many different types of leukemia.