I am a beginner at avaloniaUI and MVVM Community toolkit.
Now, I’m making an KanbanBoard windows app and coding ViewModels.
I red SimpleToDoList in their github. However i cannot understand these keywords.

Their viewmodel, is

public partial class MainViewModel : ViewModelBase

however some MVVM Community toolkit are

public partial class MainViewModel : ObservableObject
OR
public partial class MainViewModel : ObservableCollection
OR
public partial class MainViewModel : ObservableRecipient

I would like to know them.
1)how difference to use these keywords.
2)which should I use key words to my ViewModel which show and save Kanban about Task or Job.

please reply thx.

Ill apologize to my poor english skill.