extern -- C# Keyword

extern -- C# Keyword

•  The extern modifier is used to declare a method that is implemented externally.
• A common use of the extern modifier is with the DllImport attribute when you are using Interop services to call into unmanaged code.
• In this case, the method must also be declared as static, 

[DllImport("<dll Name>.dll")]
private static extern void <dll Method Name>();