As an exercise, try creating a .emacs file of your own and add that line to it. Then exit and start Emacs again. You should not see the welcome message. And customize was born. Customize provides a more intuitive method of customizing parts of Emacs.
Some groups contain sub-groups.
If you make changes using the customize interface, Emacs will save the changes to your .emacs file. I don't use the Customize interface, so I can't say much more about it. Like any well behaved X application, Emacs respects your X resources. That means you can control the initial colors, geometry, and other X specific things just as you could with an xterm, nxterm, or whatever. 80x25 See your X manual page for more details about X resources.