Physical Layer

Lastly, at the very base of the OSI model, exists the Physical Layer.  This layer provides the electrical, mechanical, and functional methods to move the actual bits of data (the 1s and 0s that encompass data in its raw forms) between networking and computing devices in order to facilitate the transparent transmission of bit streams between Data Link protocols. This movement of data is supported by various forms of media (both wired and wireless). Examples include copper cables or wireless channels. Data being transmitted across these various forms of media may flow in either half-duplex mode (in one direction at a time) or in full-duplex mode (in both directions simultaneously). Devices that operate at this layer include hubs and repeaters.