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A variable is a container that you can store
a value in. When you use that variable in

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an algorithm, it opens up the container and
looks at the value inside. This lets you write

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smarter algorithms that behave differently
depending on the value stored in the variable.

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Now you're going to try playlab where you
are given different games and you can change

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the values of variables like speed, height,
score, in order to change the game. You won't

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have to change the algorithm of the game to
change how it plays, just the variable. In

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my work for Kindle and on X-ray for books,
we apply variables in many different ways.

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One way that you can use a variable is to
store page numbers of a book. A user can increase

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and decrease the size of the font on a page.
Based on the font size, the number of pages

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in the book can change. We can adjust it by
storing the number of pages in the variable.