seal

Sealed class: class can not be inherited sealing, sealing can not abstract class

    public sealed class Father
    {
        public  virtual void Eat()
        { 
        
        }
    }

Sealing method: only for overridden method

    public  class Son: Father, IFather 
    { 
        public  Sealed  the override  void Eat. () 
        { 
            // overwriting method abstract subclass 
            Console.WriteLine ( " virtual method overwriting " );      
        } 
    }