Change Emacs syntax highlighting colors

I'm running Emacs, editing files in C++ mode and PHP mode. I love syntax highlighting as a concept, but the default colors are a travesty. I can barely read some of them: way too dark. What is the easiest way to change their values? I can't seem to find anything about this on the web. I don't even mind changing the binary as I'm compiling my own Emacs. I just want to find the place where it says blue is #0000FF and change it to #AAAAFF for example.

I find it easiest to use color-theme for this sort of thing.

But if you don't want to do that, put the cursor over the offending text, and hit M-x customize-face. It should default to the face that the cursor is over.

See 49.1.6 Customizing Specific Items.

Two ways - you can install the package color-theme, which has lots of nice schemes to select and is easier to do it by hand. The by-hand looks like this (in your .emacs file)

(custom-set-faces
   custom-set-faces was added by Custom.
   If you edit it by hand, you could mess it up, so be careful.
   Your init file should contain only one such instance.
   If there is more than one, they won't work right.
  '(default ((t (:inherit nil :stipple nil :background "lightyellow2" :foreground "gray20" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight bold :width normal :family "liberation mono"))))
  '(background "blue")
  '(font-lock-builtin-face ((((class color) (background dark)) (:foreground "Turquoise"))))
  '(font-lock-comment-face ((t (:foreground "MediumAquamarine"))))
  '(font-lock-constant-face ((((class color) (background dark)) (:bold t :foreground "DarkOrchid"))))
  '(font-lock-doc-string-face ((t (:foreground "green2"))))
  '(font-lock-function-name-face ((t (:foreground "SkyBlue"))))
  '(font-lock-keyword-face ((t (:bold t :foreground "CornflowerBlue"))))
  '(font-lock-preprocessor-face ((t (:italic nil :foreground "CornFlowerBlue"))))
  '(font-lock-reference-face ((t (:foreground "DodgerBlue"))))
  '(font-lock-string-face ((t (:foreground "LimeGreen"))))

...

etc. etc.

You can also type

`M-x customize-face RET`

which will give you all the customizations to set, ultimately end up in your .emacs file.

Put the cursor on a face ("color") that you want to change. Hit C-u C-x =. That will tell you which face(s) are present at that position, and it will let you click to customize it/them. Save your customizations.

If you don't care about color highlighting at all, or none of the previous answers work for you (or take too much time and effort to figure out), here is a very simple solution that will get rid of colors altogether.

Typing the following will get rid of colors:

M-x global-font-lock-mode

You can also do this as an interim step to allow you to actually see everything your screen to try any of the above answers. In my case, this was very useful because the color of certain key pieces of text which would allow me to change colors were themselves nearly invisible - for instance, the prompt of M-x.

If you want the change to be permanent, you can add this to your .emacs file:

(setq-default global-font-lock-mode nil)

Starting with Emacs 24.1, you can use M-x customize-themes to select a colour theme.

Emacs comes with a dozen or so themes with varying brightness and colourfulness, so you'll most likely find something that mostly matches your preferences.

You can also find more colour themes installable through MELPA at https://peach-melpa.org/.