Question:What is data binding in AngularJS? 

AngularJS data-binding is the most useful feature which saves you from writing boilerplate code (i.e. the sections of code which is included in many places with little or no alteration). Now, developers are not responsible for manually manipulating the DOM elements and attributes to reflect model changes. AngularJS provides two-way data-binding to handle the synchronization of data between model and view.

Question:Explain Two-way and One-way data binding in AngularJS? 

Two-way data binding - It is used to synchronize the data between model and view. It means, any change in model will update the view and vice versa. ng-model directive is used for two-way data binding.

One-way data binding - This binding is introduced in Angular 1.3. An expression that starts with double colon (::), is considered a one-time expression i.e. one-way binding.

Question:How AngularJS handle data binding? 

AngularJS handle data-binding mechanism with the help of three powerful functions: $watch(), $digest() and $apply(). Most of the time AngularJS will call the $scope.$watch() and $scope.$digest() functions for you, but in some cases you may have to call these functions yourself to update new values.