AngularJS let you build properly structured web applications very easily. For that, AngularJS contains several concepts to separate the different parts of your application.
Expressions in your HTML page are nice, but you won’t build a complete web application like that, it would be horrible to write and to maintain, we need the help of something more powerful. Expressions are used for small operations, In order to structure you web application, AngularJS will give you a much impressive tool, directives.
Directives are one of the most powerful feature of AngularJS. They allow you to extend HTML to answer the needs of web applications. Directives let you specify how your page should be structured for the data available in a given scope. We will have a look at the scope and where those data are coming from later in this post but first let’s have a look at how directives are working.