The physical layer forms the first layer in the OSI model, the standardized reference model for structuring network communication.
This layer is responsible for transforming the bits of a data packet into a suitable signal that is compatible with the transmission medium. This transformation takes place in the form of a physical transmission, such as copper wire, fiber optics or air. The physical layer acts as an electrical, mechanical and functional interface, using various protocols and standards such as DSL (Digital Subscriber Line), ISDN (Integrated Services Digital Network), Bluetooth, USB or Ethernet.
It thus enables communication between devices in a network.