What is the role of the Physical Layer in the OSI model?

Layer 1 takes a finished frame from the Data Link layer, encodes it into signals (electrical, light, or radio), and puts those bits onto the physical media — the last step of encapsulation.

The Physical Layer (Layer 1) transports bits across the network media.

Functions:

1. Accepts a complete frame from the Data Link Layer
2. Encodes it as a series of signals transmitted to the local media
3. This is the last step in encapsulation

At the receiving end:

• The next device receives the bits
• Re-encapsulates the frame
• Decides what to do with it

Go deeper:

• Physical layer — Wikipedia — what Layer 1 does: transmitting and receiving the unstructured raw bits onto the media.

• OSI model — Wikipedia — places the physical layer at the bottom of the seven-layer stack, showing what hands it the frame.