Declaring a variable is defining it for the first time.
When declaring a variable in Javascript, you use var in front.
For example, this creates a variable named numApples that has no value yet.
var numApples;
Later, you can initialize it by typing
numApples = 2;
which sets the value of numApples.
This declares and initializes a variable numOranges with a starting value of 4.
var numOranges = 4;
Declaring is different from updating the value of a variable. Here’s an example:
var points = 5; // declares the points variable and sets its value to 5
points = 10; // updates the value of the points variable to 10