Readonly Collections are Wrappers over the Read/Write Collections

    class Program
    {
        static void Main(string[] args)
        {
            //Readonly Collections are Wrapper over the Read/Write Collections
            ObservableCollection<string> _observableCollection = new ObservableCollection<string>() { "Mitica", "Dragomir"};
            ReadOnlyObservableCollection<string > _readOnlyObservable = new ReadOnlyObservableCollection<string>(_observableCollection);

            _observableCollection.Add("Gigi");
            //_observableCollection and _readOnlyObservable have both 3 items.

            List<string> _list = new List<string> { "Mitica", "Dragomir" };
            List<string> _list2 = new List<string>(_list);//here is created a new list of pointers
            ReadOnlyCollection<string> _collection = new ReadOnlyCollection<string>(_list);
            
            _list.Add("Gigi");
            //_list has 3 items  // _list2 has 2 items // _collection has 3 items

            
        }

    }