Описание тега angularjs-directive
AngularJS directives are a way to teach HTML new tricks by extending the HTML vocabulary. Directives allow you to manage DOM elements in a declarative pattern, freeing you from low level DOM manipulation tasks.
Directives are a way to teach HTML new tricks. During DOM compilation directives are matched against the HTML and executed. This allows directives to register behavior, or transform the DOM.
A directive is a behavior or DOM transformation which is triggered by the presence of a custom attribute, element name, or a class name. A directive allows you to extend the HTML vocabulary in a declarative fashion.
Angular comes with a built in set of directives which are useful for building web applications but can be extended such that HTML can be turned into a declarative domain specific language (DSL).
One can create his/her own custom directives in order to have own manipulations according to one's requirement.