public class Class1
    {
        int i;				//No Access specifier means private
        public int j;			// Public
        protected int k;			//Protected data
        internal int m;			// Internal means visible inside assembly
        protected internal int n;		//inside assembly as well as to derived classes outside assembly
        static int x;			// This is also private
        public static int y;		//Static means shared across objects
        [DllImport("MyDll.dll")]
        public static extern int MyFoo();  	//extern means declared in this assembly defined in some other assembly
        public void myFoo2()
        {
            //Within a class if you create an object of same class then you can access all data members through object reference even private data too
            Class1 obj = new Class1();
            obj.i = 10;	//Error can’t access private data through object.
            obj.j = 10;
            obj.k = 10;
            obj.m = 10;
            obj.n = 10;
            //     obj.s =10;  //Errror Static data can be accessed by class names only
            Class1.x = 10;
            //   obj.y = 10; //Errror Static data can be accessed by class names only
            Class1.y = 10;
        }
    }

    public class Class2:Class1
    {
        int publicDataFromBase, protectedDataFromBase, internalDataFromBase, protectedInternalDataFromBase;
        public void foo()
        {
            publicDataFromBase = j;     // Data was public so can be inherited.Access through member function as well as object of child
            protectedDataFromBase = k;  // Data was protected so can be inherited.Access through member function only
            internalDataFromBase = m;   // Data was internal so can be inherited.Access through member function as well as object of child
            protectedInternalDataFromBase = n; // Data was protected internal so can be inherited.Access through member function as well as object of child
            y = 10;                     //Static data can be inherited.Data was public so can be inherited.Access through member function as well as object of child
        }
    }

Function present in base class not present in child class.
public class MyClass
    {
        public void foo()
        { 
         Console.WriteLine(“Base version of foo”);
        }
    }

    public class MyChild : MyClass
    { 
     
    }