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One of the most important concepts in computer
science is how to define new commands, how

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to add your own words to a computer language.
Most computer languages have only about one

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hundred words or commands. The art and magic
is in defining your own new words out of these

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building blocks. We do this all the time in
sports. For example, in basketball, you start

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by learning how to dribble, how to do a lay-up,
how to rebound. Once you've learned these

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really basic moves, you learn new moves and
put together these building blocks, like a

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pick and roll or give and go. You can then
go from there to do more complex plays. Once

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you learn that play and give it a name, everybody
on the team knows how to do it. Similarly

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once you've taught a computer how to do an
action once using these sequences of commands,

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you can make up your own name for that action
so it's easy to repeat it later. When you

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define your own command and give it a name,
that's called a function. Now we're going

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to use functions to help the bee. In this
example, our function is called get 2 nectar,

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this green block right here. We know what
get 2 nectar does by looking at this grey

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box which is the function definition. If we
look inside there, the get 2 nectar is going

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to get nectar and then get nectar again. Always
look at what's inside the grey box so that

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you know what these green function blocks
can do.