Passing a reference with keyword ref gives the called method control over the passed reference itself.

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Quizplus · Accepted Answer

When a reference is passed with the keyword ref, the called method can change the value of the parameter and this change is then visible to the calling method as well. This is because the called method is given control over the passed reference itself, which allows it to modify the original object that the reference points to.

Passing a Reference with Keyword Ref Gives the Called Method