[MUSIC]

At the most basic level, when a computer runs an application,

it follows the list of instructions you or another person has written.

This list of instructions is called a program.

Often programs take in or spit out some form of data.

Whether you're checking the weather or writing a paper,

programs are constantly handling data.

Data [SOUND] itself is a piece or pieces of information.

Almost all data is ultimately represented in [SOUND] binary form.

Meaning [SOUND] data at its essence is just a series of 0s and 1s.

[SOUND] These binary digits, 0 and 1,

can be represented easily using electrical circuits.

A bit, which is like a switch, is either off or on.

If the switch is off, it's a 0.

If it's on, it's a 1.

An easy way to visualize binary is on a circuit board.

To represent 1 and 0, we use high and low voltages to turn an LED on and off.

Let's use this Texas Instrument launch pad for a tangible example of binary.

We're using HIGH to turn the LED on to represent the binary 1.

And to turn the LED off, we'll use LOW or the binary 0.

But say instead I wanted to loop it from on to off or 1 to 0 and back again.

I might write a program that looks like this.

Turn it on, wait for a second, turn it off, wait for a second.

Turn it on, wait for a second, turn it off, wait for a second.

Now, this code is using Energia, which we don't really teach here at Treehouse.

But if you're interested, in the teacher's notes I've linked the wiki page

that you can find on GitHub and the link to the microcontroller I'm using.

The fundamental building blocks of a computer is this idea of a switch,

on or off.

In a digital computer, this switch takes the form of a transistor.

Before digital computers, they used vacuum tubes to do this.

In order to store data or run programs, we need to first convert the programs

into something that can actually be performed by the physical hardware.

In most cases, this means turning the programs we write into binary.