Emacs Syntax Highlighting
If you use Emacs for programming, one very useful feature is syntax highlighting. To get Emacs to highlight properly, you may first need to tell it what language you are programming in; however, if you opened a file with the appropriate extension (i.e.: .c, .pl, etc...), Emacs should automatically go into the correct mode. To tell emacs to go into C mode you would type M-x c-mode. For perl, try M-x cperl-mode. There are many more modes as well. If you're unsure how to get into yours, try typing M-x followed by the beginning of the language name (i.e. ja for java) and pressing tab. Emacs will present you with a list of possible completions. Once you're in the appropriate mode, type M-x font-lock-mode, and it should display the text you're editing with all keywords and expressions highlighted nicely. I have found this to make programming much easier in general, and it also helps in quickly locating syntax errors.