You can specify colors when you use Emacs with the MIT X Windowing system.
I dislike the default colors and specify my own.
Here are the expressions in my .emacs file that set values:
;; Set cursor color (set-cursor-color "white") ;; Set mouse color (set-mouse-color "white") ;; Set foreground and background (set-foreground-color "white") (set-background-color "darkblue") ;;; Set highlighting colors for isearch and drag (set-face-foreground 'highlight "white") (set-face-background 'highlight "blue") (set-face-foreground 'region "cyan") (set-face-background 'region "blue") (set-face-foreground 'secondary-selection "skyblue") (set-face-background 'secondary-selection "darkblue") ;; Set calendar highlighting colors (with-eval-after-load 'calendar (set-face-foreground 'diary "skyblue") (set-face-background 'holiday "slate blue") (set-face-foreground 'holiday "white"))
The various shades of blue soothe my eye and prevent me from seeing the screen flicker.
Alternatively, I could have set my specifications in various X initialization files. For example, I could set the foreground, background, cursor, and pointer (i.e., mouse) colors in my ~/.Xresources file like this:
Emacs*foreground: white Emacs*background: darkblue Emacs*cursorColor: white Emacs*pointerColor: white
In any event, since it is not part of Emacs, I set the root color of my X window in my ~/.xinitrc file, like this1:
xsetroot -solid Navy -fg white &
 I also run more modern window managers, such as Enlightenment, Gnome, or KDE; in those cases, I often specify an image rather than a plain color.