out keyword in c sharp

out 

The out and the ref parameters are used to return values in the same variables, that you pass an an argument of a method. These both parameters are very useful when your method needs to return more than one values.

The out keyword causes arguments to be passed by reference. This is like the ref keyword, except that ref requires that the variable be initialized before it is passed. To use an out parameter, both the method definition and the calling method must explicitly use the out keyword

The out parameter can be used to return the values in the same variable passed as a parameter of the method. Any changes made to the parameter will be reflected in the variable.
public class mathClass
{public static int TestOut(out int iVal1, out int iVal2)
{
iVal1 = 10;
iVal2 = 20;return 0;
} public static void Main()
{int i, j; // variable need not be initializedConsole.WriteLine(TestOut(out i, out j));
Console.WriteLine(i);
Console.WriteLine(j);
}
}