Editing Physical layer (section)

{{short description|Lowest-level electronic or optical transmission functions of a network}}
{{Redirect|PHY}}

{{OSI model}}

In the seven-layer [[OSI model]] of [[computer network]]ing, the '''physical layer''' or '''layer 1''' is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the [[electrical connector]]s, the frequencies to transmit on, the [[line code]] to use and similar low-level parameters, are specified by the physical layer.

At the electrical layer, the physical layer is commonly implemented in a dedicated [[PHY]] chip or, in [[electronic design automation]] (EDA), by a [[semiconductor intellectual property core|design block]]. In [[mobile computing]], the [[MIPI Alliance]] [[M-PHY|*-PHY]] family of interconnect protocols are widely used. 

Historically, the OSI model is closely associated with internetworking, such as the [[Internet protocol suite]] and [[Ethernet]], which were developed in the same era, along similar lines, though with somewhat different abstractions. Beyond internetworking, the OSI abstraction can be brought to bear on all forms of device interconnection in [[data communication]]s and computational electronics.