Scope is the set of variables, objects that you have access to.

Here are some examples that will explain you about scopes :-

1.A globally-scoped variable

    var a = 1;

    // global scope
    function one() {
     console.log(a);
    }

This variable can be accessed anywhere.

2.Local scope

    function three() {
      var a = 3;
      console.log(a);
    }

This variable can only be accessed inside this function.

3.Intermediate

var a = 2;

    function four() {
      if (true) {
        var a = 5;
      }

      console.log(a); // alerts '5', not the global value of '2'
    }

This will give value of a as '5', not '2'.

4.Intermediate: Object properties

    var a = 1;

    function five() {
      this.a = 5;
    }

5.Global+Local: An extra complex Case

    var a = 2;

    (function () {
        console.log(a);
        var a = 12;
        console.log(a); 
    });

This function will give output as undefined and 12 rather than 2 and 12 since JavaScript always moves variable declarations (not initializations) to the top of the scope.

I hope these examples will give you a better insight of scopes in JavaScript.