Default threads in c# very small console application ( Visual Studio 2012 )

In brief, these extra threads are GC, Finalizer, VS, and Debugger related. The link below provides a more detailed answer to your question:

Why does this simple .NET console app have so many threads?

First of all I think we need to understand what are threads?

Threads:

Threading enables your program to perform concurrent processing so that you can do more than one operation at a time. For example, you can load a heavy images to your application, perform background tasks, and at that time you can handle a streaming to files.

If you would not use threads - then when you were loading the images to your application then your UI were stucked so you couldn't do nothing else, just waiting until the images will finish loading.

So why our application starts at 7-8 threads?

So lets see which threads we have:

By default, a C# program has one thread. This thread executes the code in the program starting and ending with the Main method.

You have also a garbage collector thread which responsible for killing objects when their life cycle ends.

And there are some more threads of debugging.