In AngularJS, event propagation in nested controllers occurs from child to parent controllers. When an event is triggered in a child controller, it can propagate up the hierarchy to parent controllers. This allows for a hierarchical communication structure, and parent controllers can handle events triggered by their child controllers. Understanding event propagation is essential for building complex AngularJS applications with nested components.

In AngularJS, a 'root scope' refers to the top-level scope that exists for the entire application. It serves as the global scope accessible to all controllers and views within the application. The root scope is created when the AngularJS application is initialized and provides a common space for sharing data and functions across different parts of the application. Understanding the concept of the root scope is essential for effective data management in AngularJS.

Directives in AngularJS play a pivotal role in dynamic view manipulation. They allow the creation of custom HTML tags and attributes, enabling developers to extend HTML syntax and create reusable components. By attaching behavior to elements, directives facilitate dynamic updates to the DOM, enhancing the flexibility and maintainability of AngularJS applications. Understanding the role of directives is essential for effective front-end development in AngularJS.

While $scope is essential for data binding and communication in AngularJS, improper use can impact the debugging process. Excessive use of $scope can make the scope hierarchy complex, making it challenging to trace variable values and dependencies during debugging. Developers may encounter difficulties understanding the flow of data between controllers and directives. Therefore, a judicious and organized use of $scope is necessary to streamline the debugging process in AngularJS applications.

The ng-model directive in AngularJS is primarily used for two-way data binding. It binds the value of HTML elements (like input, select, and textarea) to a property on the model. When the user interacts with the UI, changes are automatically reflected in the model, and vice versa. Understanding and using ng-model is essential for implementing efficient and dynamic forms in AngularJS applications.

By using Modules, $scope can avoid conflicts and ensure modularity in large AngularJS applications. Modules are a way to organize and structure an AngularJS application. They help in encapsulating code, defining boundaries, and managing dependencies, leading to a more modular and maintainable codebase. Understanding how to use Modules is essential for building scalable and organized AngularJS applications.

AngularJS's ng-model directive is used to bind HTML elements to data in the model. It creates a two-way data binding, allowing changes in the view to automatically update the model and vice versa. Understanding and using ng-model is fundamental for handling user input and updating data dynamically in AngularJS applications.

In AngularJS, when two controllers need to communicate, you can use the $broadcast and $on features. $broadcast sends an event downward to all child scopes, and $on listens for these events. This allows controllers to exchange information without being directly connected. Understanding this mechanism is crucial for implementing efficient communication between controllers in AngularJS applications.

AngularJS expressions have limitations compared to standard JavaScript expressions, including limited access to global objects. Due to security reasons, AngularJS expressions do not have direct access to the global window object or other global variables. Developers should be aware of these limitations when working with expressions in AngularJS and use them judiciously to maintain a secure and efficient application.

In MVC architecture, the Controller component is responsible for handling user interactions and managing the flow of data between the Model and View.