转：https://stackoverflow.com/questions/20016634/highlight-selected-text-in-emacs-org-mode
- In org-mode you can use word to get word in bold face, /word/ to get word in italics and word to get word underlined.
- You can re-define the characters for emphasizing via “Options->Customize Emacs->Specific Option”，then input “org-emphasis-alist”. That is permanent in the sense that if you save and kill the buffer and reload the file into emacs you have the same high-lighting again.
M-x hi-lock-mode 使能后，Edit菜单会多出一项，如图1所示：
"highlight-regexp" will ask you for a regexp to highlight and a color (there are some combinations of background and foreground).
"highlight-lines-matching-regexp" does what it means.
you can enable or disable it with "hi-lock-mode".
and you can permanently save them with “hi-lock-write-interactive-patterns (M-s h w)”. Emacs will write a bit of lisp in a commented line in your buffer.
See more tricks here: https://www.gnu.org/software/emacs/manual/html_node/emacs/Highlight-Interactively.html
http://www.masteringemacs.org/articles/2010/10/13/highlighting-by-word-line-regexp/
Enjoy !
选择颜色参考图2：
idea：hl-line
essentials：hi-blue