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[MUSIC]

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

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

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This list of instructions is called a
program.

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

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

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programs are constantly handling data.

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

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

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

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[SOUND] These binary digits, 0 and 1,

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can be represented easily using electrical
circuits.

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

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

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

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

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

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

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

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

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

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I might write a program that looks like
this.

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

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

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

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

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

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

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on or off.

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

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

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

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

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