The View Model is a part of an MVVM application responsible for the interaction between the two other parts: Model and View.
The DevExpress MVVM Framework provides base classes that you can use for deriving your View Models:
The BindableBase class implements the INotifyPropertyChanged interface and allows you to implement bindable properties with minimum coding.
The ViewModelBase class is a BindableBase descendant, which inherits its features and offers more capabilities: commands, consuming services, and interaction between View Models.
The MVVM Framework allows you to transform a POCO class into a fully functional ViewModel by creating a class instance with the ViewModelSource.Create method.
Article: POCO ViewModels
Interaction of ViewModels