A NIC is the hardware that physically connects a device to a network; a device may have several (e.g. one wired, one wireless) to attach to different networks or media.

Before any network communication can happen at all, a device needs a physical connection to a local network — and the Network Interface Card (NIC) is the piece of hardware that provides it. That connection can be wired (copper or fiber) or wireless (radio), depending on how the network is set up, and the same logic applies whether you are in a corporate office or at home.

A device can carry more than one NIC. A laptop, for example, typically has both a wired Ethernet NIC and a wireless NIC, letting it attach to different networks or media and switch between them. This matters because not all physical connections offer the same performance: a wired link is usually faster and more reliable than a wireless one, so the choice of NIC directly affects how well the device communicates.

Go deeper:

• What is a network interface card (NIC)? — TechTarget — concise definition of the NIC as the hardware that connects a device to a network.

• Network Interface Card (NIC) — GeeksforGeeks — contrasts wired (Ethernet) and wireless NICs, which is exactly why a device carries more than one.

• Network interface controller — Wikipedia — broader reference on NIC hardware and how it implements the physical layer.

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.