Which layer of the OSI model is responsible for the physical transmission of data?

The Physical Layer of the OSI model is fundamentally responsible for the actual transmission of raw bit streams over a physical medium. This layer deals with the electrical, optical, and mechanical specifications of the data transmission process. It defines how data is physically encoded and transmitted over various types of media, such as copper wires, fiber optics, or radio waves.

Key functions of the Physical Layer include converting digital data into electrical, optical, or radio signals; defining the characteristics of the transmission medium; and establishing protocols for signal timing, synchronization, and voltage levels. This level ensures that data moves over the physical connection between devices.

In the context of network communication, while the Data Link Layer provides the needed means for error detection and correction on the physical transmission, it is the Physical Layer that strictly handles the physical mechanics of the data transfer itself. The other layers, such as the Network and Transport Layers, focus more on the logical aspects of data transfer and higher-level protocols, steering clear of the actual physical transmission details.