ObservableCollection

http://msdn.microsoft.com/en-us/library/ms668604.aspx

Following information is excerpted from MSDN documentation:

Namespace: System.Collections.ObjectModel
Assembly: System (in System.dll)

Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.

The ObservableCollection<T> class, is an implementation of a data collection that implements the INotifyCollectionChanged interface. (The INotifyCollectionChanged interface exposes the CollectionChanged event, an event that should be raised whenever the underlying collection changes.)

Note:

If you ever need to implement your own collection, consider using IList, which provides a non-generic collection of objects that can be individually accessed by index. Implementing IList provides the best performance with the data binding engine.

More info:

How to: Create and Bind to an ObservableCollection