Lamda Expressions

this.button1.Click += (_sender, _e) => { System.Windows.Forms.MessageBox.Show(_sender.ToString()); };

delegate int del(int i);
static void Main(string[] args)
{
    del myDelegate = x => x * x;
    int j = myDelegate(5); //j = 25
}

using System.Linq.Expressions;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Expression<del> myET = x => x * x;
        }
    }
}

(int x, string s) => s.Length > x

delegate void TestDelegate(string s);
//…
TestDelegate myDel = n => { string s = n + " " + "World"; Console.WriteLine(s); };
myDel("Hello");

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private async void button1_Click(object sender, EventArgs e)
    {
        // ExampleMethodAsync returns a Task.
        await ExampleMethodAsync();
        textBox1.Text += "\r\nControl returned to Click event handler.\r\n";
    }

    async Task ExampleMethodAsync()
    {
        // The following line simulates a task-returning asynchronous process.
        await Task.Delay(1000);
    }
}

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        button1.Click += async (sender, e) =>
        {
            // ExampleMethodAsync returns a Task.
            await ExampleMethodAsync();
            textBox1.Text += "\r\nControl returned to Click event handler.\r\n";
        };
    }

    async Task ExampleMethodAsync()
    {
        // The following line simulates a task-returning asynchronous process.
        await Task.Delay(1000);
    }
}

MSDN Lambda Expressions