automatic and manual symbol highlighting for Emacs

Add the following to your .emacs file:

(require 'highlight-symbol)
(global-set-key [(control f3)] 'highlight-symbol-at-point)
(global-set-key [f3] 'highlight-symbol-next)
(global-set-key [(shift f3)] 'highlight-symbol-prev)
(global-set-key [(meta f3)] 'highlight-symbol-query-replace)

Use highlight-symbol-at-point to toggle highlighting of the symbol at point throughout the current buffer. Use highlight-symbol-mode to keep the symbol at point highlighted.

The functions highlight-symbol-next, highlight-symbol-prev, highlight-symbol-next-in-defun and highlight-symbol-prev-in-defun allow for cycling through the locations of any symbol at point. Use highlight-symbol-nav-mode to enable key bindings (M-p and M-p) for navigation. When highlight-symbol-on-navigation-p is set, highlighting is triggered regardless of highlight-symbol-idle-delay.

highlight-symbol-query-replace can be used to replace the symbol.