Calling Console.WriteLine from multiple threads

The console class handles the thread synchronization for you.

From the documentation of Console:

I/O operations using these streams are synchronized, which means multiple threads can read from, or write to, the streams.

Multiple threads write to the same output when using Console.WriteLine, generally your screen by default.

The console and your code are 2 seperate applications

The console window is not your application. A console application is invisable, your application does not contain the console. The console is installed into windows itself.

Console.Writeline() is a Message

It writes to a TextStream. Microsoft's console process simply waits for new streamtext to display.

The 'Console Application' name does not make it a console

The difference with ui projects is that a console application comes with a simplified set of references, and relies on input / output stream to communicate with the user.

You dont even need the console, you could build your own console, or use a debugger to view and write to it.

Comparison with notepad

If a file was a message, and notepad opened the filestream saved by your code. It wouldnt have mattered from which thread you saved the file. You are not accesing any ui.