What is viewModel in MVVM pattern?
ViewModel is a non-visual class. The ViewModel is unaware of the view directly. Communication between the View and ViewModel is through some property and binding. Models are connected directly to the ViewModel and invoke a method by the model class, it knows what the model has, like properties, methods etcetera and also is aware of what the view needs.
One View-Model can connect to multiple models, work like a one-to-many relationship and encapsulate business logic and data for the View. A ViewModel inherits some interface like INotifyPropertyChanged, icommand INotifyCollectionChanged etcetera.