Is binding in XAML only works for properties not for fields

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XAML

WPF

C#7.0

I tried Binding in XAML, while binding i encountered this issue

<pre lang="c#">

public class StudentsCollectionViewModal
    {
        public List<Author> studentCollection 

       = new List<Author>();

        public StudentsCollectionViewModal()
        {
            studentCollection = LoadCollectionData();
        }
        private List<Author> LoadCollectionData()
        {
            List<Author> authors = new List<Author>();
            authors.Add(new Author()
            {
                ID = 101,
                Name = "Mahesh Chand",
                BookTitle = "Graphics Programming with GDI+",
                DOB = new DateTime(1975, 2, 23),
                IsMVP = false
            });
            authors.Add(new Author()
            {
                ID = 201,
                Name = "Mike Gold",
                BookTitle = "Programming C#",
                DOB = new DateTime(1982, 4, 12),
                IsMVP = true
            });
            authors.Add(new Author()
            {
                ID = 244,
                Name = "Mathew Cochran",
                BookTitle = "LINQ in Vista",
                DOB = new DateTime(1985, 9, 11),
                IsMVP = true
            });
            return authors;
        }
        public class Author
        {
            public int ID { get; set; }
            public string Name { get; set; }
            public DateTime DOB { get; set; }
            public string BookTitle { get; set; }
            public bool IsMVP { get; set; }
        }
    }
}

here is XAML code where i tried binding

<UserControl.DataContext>
        <viewModal:StudentsCollectionViewModal></viewModal:StudentsCollectionViewModal>
    </UserControl.DataContext>
    <Grid Background="SkyBlue">
        <DataGrid Margin="10" x:Name="datagrid" ItemsSource="{Binding studentCollection}" RowBackground="LightYellow"
 AlternatingRowBackground="LightSkyBlue" AlternationCount="2" AllowDrop="True" >
        </DataGrid>       
    </Grid>

as per my expectation binding didn't work , but when i changed "studentCollection" field to properties

public List<Author> studentCollection 

       = new List<Author>();

to

private List<Author> _studentCollection;

       public List<Author> studentCollection
       {
           get { return _studentCollection; }
           set { _studentCollection = value; }
       }

it worked.

whole modified class

public class StudentsCollectionViewModal
    {
        // public List<Author> studentCollection = new List<Author>();

        private List<Author> _studentCollection;

        public List<Author> studentCollection
        {
            get { return _studentCollection; }
            set { _studentCollection = value; }
        }

        public StudentsCollectionViewModal()
        {
            studentCollection = LoadCollectionData();
        }
        private List<Author> LoadCollectionData()
        {
            List<Author> authors = new List<Author>();
            authors.Add(new Author()
            {
                ID = 101,
                Name = "Mahesh Chand",
                BookTitle = "Graphics Programming with GDI+",
                DOB = new DateTime(1975, 2, 23),
                IsMVP = false
            });
            authors.Add(new Author()
            {
                ID = 201,
                Name = "Mike Gold",
                BookTitle = "Programming C#",
                DOB = new DateTime(1982, 4, 12),
                IsMVP = true
            });
            authors.Add(new Author()
            {
                ID = 244,
                Name = "Mathew Cochran",
                BookTitle = "LINQ in Vista",
                DOB = new DateTime(1985, 9, 11),
                IsMVP = true
            });
            return authors;
        }
        public class Author
        {
            public int ID { get; set; }
            public string Name { get; set; }
            public DateTime DOB { get; set; }
            public string BookTitle { get; set; }
            public bool IsMVP { get; set; }
        }
    }

So i have this query is binding in XAML works only on properties not on fields.

What I have tried:

I tried google but couldn't find any dent so tried over my XAML application to understand.