<P> The physical layout of a network is usually less important than the topology that connects network nodes . Most diagrams that describe a physical network are therefore topological, rather than geographic . The symbols on these diagrams usually denote network links and network nodes . </P> <P> The transmission media (often referred to in the literature as the physical media) used to link devices to form a computer network include electrical cable, optical fiber, and radio waves . In the OSI model, these are defined at layers 1 and 2--the physical layer and the data link layer . </P> <P> A widely adopted family of transmission media used in local area network (LAN) technology is collectively known as Ethernet . The media and protocol standards that enable communication between networked devices over Ethernet are defined by IEEE 802.3 . Ethernet transmits data over both copper and fiber cables . Wireless LAN standards use radio waves, others use infrared signals as a transmission medium . Power line communication uses a building's power cabling to transmit data . </P> <P> The orders of the following wired technologies are, roughly, from slowest to fastest transmission speed . </P>

Radio waves used to connect computers and other devices to the internet are known as