What does the Physical Layer (Layer 1) in the OSI model address?

The Physical Layer, which is the first layer of the OSI model, is primarily concerned with the electrical, mechanical, and functional interfaces that enable communication between devices. This layer defines the physical characteristics of the network medium used for transmission, including aspects such as voltage levels, timing of voltage changes, physical data rates, and the physical layout of the network's hardware components, such as cables and connectors.

This layer serves as the foundation for the entire OSI model, facilitating the actual transmission of raw bit streams over a physical medium, such as copper wire, fiber optic cables, or wireless signals. It does not handle any higher-level functions such as data formatting or error correction, which are managed by the layers above it in the OSI model. Thus, the emphasis on electrical and mechanical parameters is key to understanding the role of the Physical Layer in network communication.