Uncaught ReferenceError: angular is not defined

Problem : This error will come when we are referring angular like "var app = angular.module('myApp',[]);" before loading angular.js files.
Sample Code that leads to error:
<script>
var app = angular.module('myApp',[]);

app.directive('myDirective',function(){

return function(scope, element,attrs) {
element.bind('click',function() {alert('click')});
};

});
</script>
<script src="lib/angular/angular.js"></script>
Solution : Just include angular.js files at the top of page before referring it.
Modify above code like this
<script src="lib/angular/angular.js"></script>
<script>
var app = angular.module('myApp',[]);

app.directive('myDirective',function(){

return function(scope, element,attrs) {
element.bind('click',function() {alert('click')});
};

});
</script>

How to find Which edition of Salesforce we are using

Steps :
Step 1: Go to setup --> Click on Administer as shown in image below.

Step 2: On clicking "Administer" link,you will find the screen as shown in image below.

At the top Middle of screen, you will find the edition of salesforce you are using as highlighted in the image above.