Question

In some ASP.NET examples i see that events are used with delegates like this and sometimes without them like this.

Please explain!

Answer 1

All events are delegate types (they all inherit from EventHandler that inherits from MulticastDelegate which interits from Delegate). Sometimes (or I would rather say most of the time) there is no need to declare your own custom delegate for an event though. You can use existing delegates as long as they match the signature of your event. With the introduction of EventHandler<T> in .NET Framework 2.0, the need for custom event delegates pretty much disappeared (as long as you follow the event design of the framework). So, doing the following:

// declare an event with a custom delegate type
public delegate void MyCustomEventHandler(object sender, EventArgs e);
public event MyCustomEventHandler SomeCustomEvent;

…is equivalent of this:

// declare an event with an existing delegate type
public event EventHandler SomeCustomEvent;

Should you have some custom EventArgs class, you can instead use the generic EventHandler<T> for your events:

class MyCustomEventArgs : EventArgs
{
    // you custom stuff here
}

public event EventHandler<MyCustomEventArgs> SomeCustomEvent;