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Nice work! This lesson introduced you to variables, a powerful concept you will use in all your future programming endeavors.

Let’s review what we learned:

Variables hold reusable data in a program and associate it with a name.
Variables are stored in memory.
The var keyword is used in pre-ES6 versions of JS.
let is the preferred way to declare a variable when it can be reassigned, and const is the preferred way to declare a variable with a constant value.
Variables that have not been initialized store the primitive data type undefined.
Mathematical assignment operators make it easy to calculate a new value and assign it to the same variable.
The + operator is used to concatenate strings including string values held in variables.
In ES6, template literals use backticks ` and ${} to interpolate values into a string.
The typeof keyword returns the data type (as a string) of a value.

To learn more about variables take on these challenges!

Create variables and manipulate the values.
Check what happens when you try concatenating strings using variables of different data types.
Interpolate multiple variables into a string.
See what happens when you use console.log() on variables declared by different keywords (const, let, var) before they’re defined. For example:

console.log(test1);

const test1 = 'figuring out quirks';

Find the data type of a variable’s value using the typeof keyword on a variable.
Use typeof to find the data type of the resulting value when you concatenate variables containing two different data types.

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