Now networks can get really big.
Biggest network that we know of today.
Unless you know about aliens having a bigger network somewhere out there in space is the Internet.
So the Internet is the biggest network that we have on Earth today.
But a network doesn't have to be very big.
A small network would simply consist of two computers.
So in this example I've got two Windows laptops previously as I mentioned I could copy a file onto this
USB drive.
So copy a file from this computer onto the drive and then put it into the second computer and then copy
the file onto this computer.
So that's how I could share information from one computer to another without a network.
But in its most basic form a computer network will use something like a cable.
This is a copper Ethernet cable.
This is what's called UTP or Unshielded Twisted Pair copper cable.
You've probably come across these types of connectors in the real world.
This is known as an RJ45 connector.
Now it does have a different name but we won't get into that right now.
This is commonly referred to as an RJ45 connector.
So if you talk about RJ45 in a networking context people will know what you're talking about.
So I could as an example take this cable and then plug it into this laptop.
Now this is an older laptop so it has a built-in Network Interface Cards so I can take an RJ45 connector
and plug it directly into this computer.
This laptop however on the right is a newer laptop and like a lot of newer laptops and Mac books it
doesn't have any RJ45 Network Interface Cards.
Now a Network Interface Card or NIC is how we connect to the physical network or wireless network.
It's basically a card that's either inserted into a laptop or is built into a laptop that has what's
called a MAC address or Media Access Control address on Ethernet which is the technology that we generally
use today on wireless devices are known by what's called a MAC address.
So here's an example of a very old Network Interface Card this Network Interface Card supports
older technologies such as 10base5 the first type of Ethernet that was ever developed supports
10base2 and it also supports an RJ45 connector using UTP or Unshielded Twisted Pair.
This would be inserted in a computer.
Now that's really old.
Today we have more modern unshielded such as this one only supports RJ45.
It's a lot smaller.
And then this is an example of a Network Interface Card that would go in a Raspberry Pi as an example.
This only supports Wi-Fi.
I mean you can't connect Ethernet to this.
So on a laptop like this what I could do is I could use a USB to RJ45 Network Interface Card
So this is an adapter that converts a USB to RJ 45.
And then what I can do is plug the Ethernet cable in here and what I have now is essentially a network.
I have a network consisting of two windows computers
and I'll now be able to share files from one computer to the other.
But it's a lot of hassle a lot of work setting this up.
But that's an example of an Ethernet network.
where I have two computers connected using a physical cable
In this example what's called Cat 5e cabling unshielded-twisted pair RJ45 connectors on the end.
That's an example of a very basic network.
But if I told a young person today.
So let's say a teenager to set up a network between their devices using cabling like that they'd probably
think I'm crazy because what we tend to use today is Wi-Fi.
Wi-Fi is an example of using the air for transmission of data from one device to the other makes life
a lot easier
in many ways. People today expect that it's easy to share information from one device to another.
In this example I've got two iPhones.
I mean how would I physically plug a cable into one of these phones.
They don't have RJ45 connectors I don't have a USB to Ethernet port that I can use to plug an Ethernet
cable into the iPhone.
I could use the lightning port but people today wouldn't be happy with that.
They expect it to just work and work very easily.
And the technologies that we're going to be using to share files from one phone to another are Wi-Fi
as well as Bluetooth.
So as an example on this phone here's a picture I'm going to share that picture using airdrop notice
it tells me that Bluetooth is off. I need Bluetooth to allow this device to share the file with other
devices.
Now it's picked up two devices I've got a iPhone Blue which is the phone on the right as well as my
MacBook which is in front of me.
So I'm going to select the iPhone.
And what happens now is the file is shared from one phone to the other.
So by leveraging Wi-Fi and Bluetooth I can share a file from one phone to the other.
That's an example of file sharing I'm sharing a file which in this example is a picture from one phone
to the other.
And the medium or media that I'm using is the air I'm sharing data from one device to another using
Waze through the air just like I'm speaking to you.
And what's happening is a microphone is picking up the waves that I'm making with my vocal cords.
Basically speaking into the air making waves.
That's then digitized by microphone.
Same idea here a digital file on a phone is modulated in the air sent across through airwaves from one
device to the other this device to modulate it and creates the file on the other side.
So I'm transmitting a resource a file from one device to the other using the air.
In this example that's an example of a network.
I've got a network of two devices where one device is sharing a resource with another device.