Question

What is the difference between eventOne (with keyword ‘event’) and eventTwo (w/o keyword)?

class Program {     public event EventHandler eventOne;     public EventHandler eventTwo;      public void RaiseOne()     {         if (eventOne != null)             eventOne(this, EventArgs.Empty);     }      public void RaiseTwo()     {         if (eventTwo != null)             eventTwo(this, EventArgs.Empty);     }      static void Main(string[] args)     {         var p = new Program();         p.eventOne += (s, e) => Console.WriteLine('One');         p.eventTwo += (s, e) => Console.WriteLine('Two');         p.RaiseOne();         p.RaiseTwo();     } } 

Answer 1

• eventOne is a public event backed by a private field of type EventHandler.
• eventTwo is a public field of type EventHandler.

Basically an event only encapsulates the ideas of ‘subscribe’ and ‘unsubscribe’ in the same way that a property only encapsulates the ideas of ‘get’ and ‘set’ rather than the actual storage. (As far as the CLR is concerned an event can also expose a ‘raise’ method, but C# never uses this. Ignore it.)

See my article on events (alternate link) for more about the difference between delegates and events.