Talking with a faraway computer

To a faraway friend

With just my one computer
I can write and draw on my own.
But what if I want to send
that writing to a friend far away?
The two computers need
some path that links them.
Once that path exists,
I can finally say something.

Tap the two computers in turn to link them. Once a path forms, a message crosses over.

Once the two computers were linked,
the words crossed over despite the distance.
Linking computers like this
so they talk to each other,
that's the first step of a network.
But what is that "path"
actually made of?
Let's see what the path is next.

What do we link them with

There are two main ways to link computers.
One is a wire.
A visible cord
joins the two computers directly.
The other is wireless.
No cord, signals fly through the air.
Wi-Fi is exactly wireless.
Either way, the job is to make a path.

Tap to switch between wire and wireless. Both are paths that link computers the same way.

Wire or wireless,
the job was the same.
Between the two computers,
open a path for signals to travel.
The wire you can grab,
the wireless you just can't see.
So along that path,
what is it that travels?

It's 0s and 1s after all

The letters or pictures I send
change shape as they cross the path.
We learned it earlier.
Everything inside a computer
is, in the end, 0s and 1s.
A message is the same.
It turns into a string of 0s and 1s,
becomes a signal, and crosses.
The computer on the other side
turns that string back into letters to read.

Tap send. The letters turn into a signal of 0s and 1s, cross over, and become letters again on the other side.

The letters turned into 0s and 1s
and came back into letters.
What travels over the path
is always this one signal.
Photos, voices, videos,
look inside and they're all 0s and 1s.
That's why one same path
can send all kinds of things.

Many of them like a web

If only two computers are linked,
just those two talk.
But the world has so many computers.
Three, four, countless computers,
what happens if you link them all together?
Wires and signals weave like a web,
so starting from any computer
you can reach the one you want.

Tap the computers in turn to link them. Woven like a web, any two can reach each other.

Once the web was all woven,
even computers far apart
reached each other through others.
Not right next door,
but the signal crossed by passing through the middle.
Countless computers like this,
tied like a web across the whole world,
that big web we call the internet.

Let's wrap up

Gathered on one line, it's this.
A network is computers far apart
trading signals to talk.
You make a path by wire or wireless,
and the words traded are, after all, 0s and 1s.
When many tie together like a web,
you can reach anyone,
and that big web is the internet.

Tap the key points in order to review. (link afar → wire or wireless → 0 and 1 signal → like a web = internet)

Now you know what a network is.
Linking far, by signal, in a web.
But among computers tied like a web,
how does the signal I sent
find exactly that one computer among so many?
That story of finding the way,
let's follow together in the next lesson.