Data binding is a new model for application to interact with data. If data binding is established between the data, and UI, then, when data changes its value, the UI reflect changes automatically.

Data binding has several advantages over traditional models.
   1. Code for data binding is simple and small.
   2. Separation between data and UI is clear.
   3. Interaction between data and UI occurs automatically.

The source code of WPF application has two parts, which are Code and XAML.
Code is general c# code exsited from .NET 1.0, whereas XAML is additional part from .NET 3.0.
In WPF, Code process the logic and XAML process UI.
When compling the code and WPF, compiler look these and mix up into the application.

Data binding is useful to connect data in the code into UI in the XAML. It is just like plugging power code.
After data binding, all thing for interaction is done automatically. This is the thing I like mostly.

To help your understanding about data binding, let's compare the data binding with traditional model. In the traditional one, event handling function is needed for interaction. So we must write the function as much as we need interaction. For examples, if need five interactions between data and UI, we have to make five functions manually.

"Manually" is important part. :)

In new model which uses data binding, event handling function is not used any more. Only to do is declaring data binding between the data and UI. The following figures show the difference between additional model and new one. New model seems simpler than the older.

Let's make a simple data binding. First, create new WPF project. After that, add the following data class next to the default window class.