lambda expression and event handler?

You can use a lambda expression to build an anonymous method, which can be attached to an event.

For example, if you make a Windows Form with a Button and a Label, you could add, in the constructor (after InitializeComponent()):

 this.button1.Click += (o,e) =>
     {
        this.label1.Text = "You clicked the button!";
     };

This will cause the label to change as the button is clicked.