Learn about the programming concept known as variables. 

Variables

The strong selling point of using a variable is that we can easily change their value, making our programs flexible. 

As we saw in the last exercise, we can save a number to a variable and reuse it throughout a program:

```js
my_number = 847595593392818109495
my_number * 2
my_number / 4
```

We could easily switch out the value of my_number, without having to change that number in multiple places in our code. 

```js
my_number = 1
my_number * 2
my_number / 4
```

We could also change the value of `my_number` part way through our program:

```js
my_number = 1
my_number * 2

my_number = 3
my_number / 4
```


Changing the Value of a Variable 

Congrats! Now you've learned about variables and why they're useful in programming.
In this lesson, we learned that: 
- _Variables_ allow us to store information
- Variables allow us to quickly _reuse_ a value in our program.
- Variables let us easily _change_ a value in our program.  

In the next lesson, we'll look at different kinds of information that we can use in a program and save to variables. 

Review - Variables

Now that you know a bit about variables, let's code some ourselves! 

We create or _declare_ a variable by giving it a name and setting it equal to a value. 

```js
terrain = 'lake'
```

In the code editor, we've written out an example of a variable declaration. We've included one variable in the workspace, named `one`, and it's currently set to `'grass'`. 



Putting it All Together

In programming, we have a way of storing values so that we can reuse them throughout our program or change them, if necessary. This concept is known as a _variable_. 

Maybe you're familiar with the math term _variable_, or the word _variability_. Programming variables share qualities with each. Similar to a variable in math, a variable is a way of saving a piece of information with a specific name. By giving a value a name, we can easily reuse that value over and over again in our code. Like the idea of variability, a programming variable allows us to easily change a value throughout our code.

Variables are an important first step in coding because with variables we can start using an important programming tool: repetition. Rather than writing out a piece of data every time we need it, we write it out once and the computer remembers it and can repeat that information back. 

In this lesson, we'll explore why variables are an important part of programming, including:

- Using variables to reuse a value
- Using variables to change a value 


Introduction to Variables

One reason we use variables is that they allow us to easily _reuse_ values in different parts of our code. 

When we reuse a value, it will appear in multiple places in our code. Re-typing that value becomes tedious, which leads to errors, and without a variable name, it becomes unclear as to what the value represents. It may also be unclear as to what that value is meant to represent. 

Let's take a look at the following piece of code. Here we have a number that we reuse in order to make some calculations:

```js
847595593392818109495
847595593392818109495 * 2
847595593392818109495 / 4
```

Rather than writing the same number over and over again, we can save it to a variable named `my_number`: 

```js
my_number = 847595593392818109495
my_number * 2
my_number / 4
```

You may be thinking, "But what if my variable name is longer than the value it stores? What's the point of a variable?" 

When we use a value without assigning it to a variable, that's known as _hardcoding_. While it's sometimes faster to initially hardcode values in your program, in the long run you'll run into trouble &mdash; especially if you need to change what those values are. 












