This is GNU Emacs, one component of the GNU operating system.
GNU Emacs 27.0.50 (build 8, x86_64-apple-darwin17.7.0, NS appkit-1561.60 Version 10.13.6 (Build 17G65)) of 2018-09-10
Copyright (C) 2018 Free Software Foundation, Inc.
Many people have contributed code included in GNU Emacs
How to contribute improvements to Emacs
Why we developed GNU Emacs, and the GNU operating system
GNU Emacs comes with ABSOLUTELY NO WARRANTY
Conditions for redistributing and changing Emacs
How to obtain the latest version of Emacs
Buying printed manuals from the FSF
Learn basic Emacs keystroke commands
See an overview of Emacs features at gnu.org