What does "Imports System.Runtime.InteropServices" mean

I'm trying to use a snippet of code from a solution that I found here:
http://www.experts-exchange.com/Programming/Languages/.NET/Q_21739204.html
I’m not sure I understand what kind form this is.

The project only comes-up with two warnings:
Unused local variable: 'size'.

And:

Variable 'class' is passed by reference before it has been assigned a value. A null reference exception could result at runtime.

I will deal with those warning in another thread but what does this line mean:
Imports System.Runtime.InteropServices
Delta526Asked:
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Jason EvansSenior Software DeveloperCommented:
Hi there.

Basically, System.Runtime.InteropServices is used when you want to interact with the Windows API eg with declaring functions for API interactions:

 <DllImport("User32", False, CallingConvention.Cdecl, CharSet.Unicode)> _
  Public Shared Function SomeWinAPIFunction() As IntPtr

(note: don't use the above code copy-and-paste style since I just typed it off the top of my head - it could be incorrect!, but you get the idea.)

You also use this namespace if you want to do COM-based development with components written in, say, VB6 or VC++ 6 as en example.

There are many classes and interfaces to be found in this namespace which help a developer interact with COM components.

Jas.
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Delta526Author Commented:
Thank you Jas,

Could this be one of the reasons the my findwindow API application does not work in VB.NET:
http://www.experts-exchange.com/Programming/Languages/.NET/Visual_Basic.NET/Q_22454660.html
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