The Singleton Design Pattern in C#

Singleton.cs

public abstract class Singleton<T> where T : class
{
   private static volatile T _instance;
   private static readonly object _locker = new object();

   public static T Instance
   {
     get
     {
       if (_instance == null)
       {
          lock (_locker)
          {
            if (_instance == null)
                _instance = Activator.CreateInstance(typeof(T), true) as T;
          }
       }
       return _instance;
     } 
  }
}