when you start Emacs, it generates two buffers: *Messages*, *scratch*.
kill ring: Text that has been killed is not gone forever but is hidden in an area called the kill ring. Only Del and C-d does not go into kill ring.
The best way to find out where .emacs resides by default on a particular system is without a doubt C-h v user-emacs-directory. The user-emacs-directory variable is platform dependent and is helpful on each and every OS.
The default buffer is the buffer that most recently disappeared; type Enter and you'll see it again.
To cycle through all your buffers: C-x + #{left_arrow}.
