What’s a Network Interface Card (NIC)?

Whether we're communicating across light, or some sort of radio waves, or sending electrons down a copper wire, we're going to need something that translates from that computer signal into a signal that goes across that media. That's what your network interface card does.

What the card actually does

Computers operate off of ones and zeros, and for the most part that's how we communicate as well. This signal, these series of ones and zeros, need to be transferred from one device to another device. But how do we do that? Some of these medias don't talk ones and zeros. For instance, radio waves are a waveform. So what we need to do is convert these ones and zeros into a waveform, send it across the air, and convert it back into ones and zeros. That's what your network interface card does. That's the part of the computer that does that translation.

Even though we can send ones and zeros across electrical signals or across light, there still is this component that needs to be added to and translated even when we're sending across those types of medias. So no matter what, you need some sort of network interface card, or NIC, that does that translation.

Why it's called a card

This is a motherboard of a computer right here. At one point in time, if I wanted it to connect into a network, I would have to slide a card into one of these slots to give it that functionality. That's why it's called a network interface card.

Nowadays, a lot of times that's built into the motherboard or built into the system. So, for instance, this one right here has an Ethernet port right here that we could connect into, and the components for that NIC are still built into that motherboard. However, we still call it a NIC, or network interface card.

This laptop has a network interface right here that's built into the motherboard, so this is another example. This is for the Ethernet, the copper cable to come in and make connection to this computer. However, another thing that we see right here is a card, so this is actually still a card, and this one is for the wireless. This is fairly common amongst laptops, that there are still network interface cards for the wireless component.

Now what we need to do to connect these two devices is take our Ethernet cord and plug it into this network interface right here, and then we plug the other side into the other board. Typically when you're connecting computer to computer, you need a special cable. That's not always the case when you're connecting equipment, but computer to computer, a lot of times that is the case.

Communicating with light

There are times that we communicate through light just by sending a signal in the open. This is an example of it. This is a remote, and if I hold down a button, you can actually see the light flashing. It's not something I can see like this, because it's infrared. It's below a signal level that our eyes can actually pick up, but the camera can pick it up, which is why we see it right there. So this is an example of communicating, sending a signal across light.

However, typically with computers we need a much faster and much more direct and much less out in the open form of communication. So what we do is we channel that light through fiber optics. Fiber optics would be a smaller cable than an Ethernet cable, and much more fragile. You need to worry about bending it. Inside that is a small fiber. In fact, you probably can't even see this, but this is a fiber that sends light through it. Now, this one's a plastic fiber, because it's not actually from a fiber optics cable, but if it were from a fiber optics cable it would be glass, and you could break it, because it's actually glass. It only bends so far.

Those fiber optics cables would then plug into the computer, into the network interface card, and the network interface card would have that light that would send the signal down that media.