What is Struct in C# ? Example?

Struct Example in C#

{
struct student
{
public int rno;
public string name;
public string addr;

public student(int vrno, string vname, string vaddr)
{
this.rno=vrno;
this.name=vname;
this.addr=vaddr ;

}

}
private void button1_Click(object sender, EventArgs e)
{
student st = new student(1, "ragesh", "bangalore");
student stt = st;
MessageBox.Show(stt.rno + " " + stt.name + " " + stt.addr);
}
}