You use the front and back buffer with double buffering. You draw to the back buffer and show the front buffer on the screen, and when the back buffer is complete, you swap the buffers and the old back buffer is now shown on the screen.
I will also answer your question in the other thread here, as it’s basically the same question asked in different ways (altough you may just not have realized it, so no problem with it). Buffer management is not provided by OpenGL, it’s provided by the platform dependent glue layer between OpenGL and the operating system. Therefore it’s impossible to do ANYTHING directly in OpenGL, without using the windowing system. Without the windowing system, you can’t create the buffers and rendering context needed for OpenGL to work.
So in short, double buffering IS possible, but not directly in OpenGL. And the reason is that OpenGL does not provide the necessary functions for create and swap the double buffers. That is up to the glue layer to provide.
Check out this place for great tutorials on OpenGL. They create double buffered applications, and the code is available for loads of platforms.