Method Parameters (C# Reference)
Updated: July 20, 2015
For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.
If a parameter is declared for a method without ref or out, the parameter can have a value associated with it. That value can be changed in the method, but the changed value will not be retained when control passes back to the calling procedure. By using a method parameter keyword, you can change this behavior.
This section describes the keywords you can use when declaring method parameters: