var message = "Hello World"; // string
    var pie = 3.14; // number 
    var num = 1 + 2.3;
    

takes the format: 

 variable_name = expression;

    alert("Hello!");
    

RESULT:

 

   var message = "Hello World!";
   alert(message);
   

Result:

How would we define a variable which contains the sum of 2 and 8 and then print that out to the screen?