Javascript closure

This purpose of this post is to demystify what closure is in Javascript.
If you are coming from a object orientated programming language background such as C# or Java, the best way you can associate Javascript closure that you are creating a object with private variable.

The local variables are similar to your private properties such that you cannot directly access it. However you can expose functions using the return to access and update your private variables. Those return functions are similar to your public functions in your OOP language.

function CreateCar(brand){
  
  var mileage = 0;
  
  return{
    report: function(){
      console.log("your "+brand+" has travelled " +mileage +" miles")
    },
    addMileage: function(distance){
      mileage += distance
    }
  };
    
}

var newCar = CreateCar("Merc");

newCar.report();
newCar.addMileage(20);
newCar.report();
newCar.addMileage(20);
newCar.report();