Throwing exceptions

When we talk about adding errors, we refer to the process as exception throwing, which is an apt visual analogy. Throwing exceptions is part of something called defensive programming, which essentially means that you actively and consciously guard against improper or unplanned operations in your code. To mark those situations, you throw out an exception from a method that is then handled by the calling code. 

Let's take an example: say we have an if statement that checks whether a player's email address is valid before letting them sign up. If the email entered is not valid, we want our code to throw an exception:

public void ValidateEmail(string email)
{
    if(!email.Contains("@"))
    {
        throw new System.ArgumentException("Email is invalid");
    }
}

We use the throw keyword to send out the exception, which is created with the new keyword followed by the exception we specify. System.ArgumentException() will log the information...