AngularJs Registering Services Factory

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We use here factories, to register our services:
angular.module('notesApp', [])
    .controller('NotesCtrl', function ($scope, notes, archive) { ... }
    .factory('archive', function () { ... }
    .factory('notes', function (archive) { ... }
Factory is most common way to in registering objects. It is very flexible and can contain sofisticated creation logik.